Summary
This video provides an extensive overview of computer hardware components, networking concepts, and essential tools. It details various internal and external computer parts, including storage, memory, and peripherals, explaining their functions and how they connect. The video also covers a wide range of networking topics, from basic connection types and protocols like TCP/IP to advanced concepts like VLANs, DNS, and network security. Furthermore, it discusses network devices such as routers, switches, firewalls, and various cabling types and connectors, along with diagnostic tools and display technologies, aiming to equip viewers with a thorough understanding of modern computing and networking infrastructure.
Key Insights
Biometric devices like fingerprint scanners provide secure identity authentication through unique physical characteristics.
For authentication purposes, a mobile device may use biometrics to confirm an identity. A biometric device is used to prove the identity of a person by recognizing unique physical characteristics. So for example, a fingerprint scanner. Fingerprint scanners are used to read a user's fingerprint to prove authentication. You would just place or swipe your finger across the fingerprint scanner and then the scanner will either grant or deny you access based on your fingerprint. And other biometrics that can be used are facial recognition, retina scans, and voice patterns.
TCP ensures reliable, ordered data delivery through a connection-oriented, three-way handshake, resending lost packets.
Whenever a computer wants to communicate with another computer, the communication between those two computers needs to be good and reliable so it can guarantee that the data is received correctly. For example, when you want to view a web page or download a file or look at an email, you'd expect to view the web page intact and in order with nothing missing. or if you're downloading a file, you would want the entire file and not just a part of the file because if data is missing or out of order, then it wouldn't be of any benefit to you. So, this is where TCP comes in. TCP stands for transmission control protocol and this is one of the main protocols used in a TCP/IP network and TCP is what is used to guarantee that all the data is received and in order because without TCP then some of the data could be missing or out of order because if you view a web page without TCP your web page could be all messed up. The images could be missing or the text could be backwards and out of order or if you download a file then you might not get the entire file or you could get the file out of order which would render the file useless. So again this is where TCP comes in. Now TCP is a connection-oriented protocol which basically means that it must first acknowledge a session between the two computers that are communicating. So the two computers verify a connection before any communication takes place. And it does this by using a three-way handshake. So the first step is that a computer will send a message called a SYN. Then the receiving computer will send back an acknowledgement message telling the sender that it has received the message. And then finally the sender computer sends another acknowledgement message back to the receiver. And then once this has taken place, data can be delivered. Another important thing to remember about TCP is that it guarantees the delivery of the data. So if a data packet goes astray and doesn't arrive then TCP will resend it.
A proxy server acts as an intermediary, forwarding client requests to the internet and returning responses, offering security, anonymity, and caching.
Now the definition of a proxy is just someone or something that has authority to do something for another person or thing. So in terms of computers and networks, a proxy is a server and a proxy server acts on behalf of clients on a network such as retrieving data for those clients. A proxy is a middleman that sits between a private network and the public internet. So for example, here we have a private network with a bunch of computers or clients. Now all of these computers have access to the internet. But as most of us know, with all these computers having the ability to access the internet, it could also create a massive security concern. Because with all of these individual computers accessing the internet, they could draw in malicious traffic that could wreck havoc inside this network. So this is where a proxy or to be more specific, a forward proxy can be beneficial. When a forward proxy server is used on this network, the proxy server is now the guardian of this network. So when all of these computers want to access the internet, they go to the proxy server instead. and then the proxy server will fetch the data out on the internet on their behalf. So by doing this this creates a safety barrier between a private network and the internet because a major benefit of a proxy is that it can regulate traffic by blocking harmful websites. And some other benefits of a proxy is that it hides the identity of clients by masking their IP addresses and using its own IP address. So when these clients connect to websites and servers out on the internet, those websites and servers only see the IP address of the proxy server and not the clients. Another benefit is that it logs user activity. A lot of organizations like to know what websites that their clients are visiting and by using a proxy, it will keep track of the websites that were visited and how long they were on those websites. And another benefit is that it can bypass restricted content. Some organizations like schools and governments may restrict access to certain websites, but by using a proxy, you may be able to bypass those restrictions and access those restricted websites. And finally, another benefit of using a proxy server is speed because a proxy can cache or store copies of websites that are frequently used by their clients. So instead of the proxy server fetching the same websites out on the internet over and over again, those websites can be stored in the proxy's cache database instead.
VPNs create secure, encrypted tunnels over public networks, protecting data and masking IP addresses for anonymity.
Now VPN stands for virtual private network. A VPN is what establishes a secure and reliable network connection over an unsecured network such as the internet. It protects your internet activity and disguises your identity as you surf the internet. So for example, when you order internet service from your ISP or internet service provider, they will set up your internet connection. And when your setup is complete, your internet activity is routed through your ISP servers, which means that your ISP can see and log all of your internet activity. so they can see every website that you visited. Now, typically this wouldn't be a problem if they kept your internet activity private. However, there is a possibility that your ISP could share your information with other third parties such as advertisers or maybe even the government. And if this were to happen, your internet activity is no longer private. But by using a VPN, your online activity will bypass your ISP server and will be redirected to another server, which is a VPN server, which means that your internet provider or any other party can no longer see what websites you are visiting. The VPN server is now your source where all of your internet activity goes through. And this has several benefits. And the first benefit is that a VPN will disguise your identity by hiding your IP address. Whenever you order internet service from a provider, they will assign you an IP address. That unique IP address is attached to your home or business. So whenever you visit a website, that website can see your IP address. But when using a VPN, websites can no longer see your IP address. They now only see the IP address of the VPN server, which effectively hides your identity, so you can surf the internet anonymously. Another benefit is that a VPN will encrypt and protect your internet data. Whenever you go on the internet, the data that you send and receive is broken down into a bunch of smaller data packets. These data packets travel across the public internet and ultimately find their way to their destination. But as they are traveling across the internet, your data can be viewed by ISPs, governments, and it can also be intercepted by hackers, especially if you use public Wi-Fi networks. But a VPN will prevent this. A VPN will encapsulate each data packet by adding an extra layer of protection to each one, which is known as tunneling. This extra layer adds a layer of protection to ensure your data is secure and kept private as it travels across the internet in a virtual tunnel. So any activity that you do on the internet such as visiting web pages or transferring files, the data is encrypted and kept private when using a VPN.
VLANs logically group network devices into separate segments, enhancing security and traffic management regardless of physical location.
VLAN stands for virtual local area network. A VLAN is a local area network where computers, servers, and other network devices are logically connected regardless of their physical location. So even if these devices are scattered in different places, it wouldn't matter because a VLAN can logically group them into separate network segments. And the purpose of a VLAN is for improved security, traffic management, and to make a network more simple. So, as an example, let's say that you have a three story office building and in this building you have computers that belong to certain departments that are mixed in with other computers that belong to other departments on the same floor. So, the red computers represent the accounting department, the blue computers represent the shipping department, and the green computers represent the support department. Now, as you can see, all these computers from these different departments are all connected to a switch, and they are all on one segment on a local area network or LAN. So, all the network broadcast traffic from the different departments are mixed in with other departments. So, the departments are all seeing each other's network traffic. Now suppose as a network administrator you wanted to separate the network broadcast traffic between these departments from each other, so that the accounting department doesn't see any traffic from support, support doesn't see any traffic from shipping and so on. Now, one way to solve this is to physically move the computers that belong to the same department and put them together, such as putting them on the same floor and deploying extra network hardware and cabling. But this could be a hassle and unnecessary work. But there is an easier way to accomplish this and that way is by creating VLANs. By using VLANs on a VLAN capable switch, you can logically create several virtual networks to separate the network broadcast traffic. So in this case, we're going to create three VLANs for three different departments. So we're going to create a VLAN for the accounting department and then create another VLAN for the support department and then create another one for the shipping department. So now as the VLANs are implemented the traffic between the three departments are isolated. So they won't see any traffic created by the other departments. They only see their own network traffic even though all the computers from the different departments are connected to the same switch. So in our example, the VLANs were created on the switch. And this is done by designating specific ports on the switch and assigning those ports to a specific VLAN. So on the switch, we'll create a VLAN for the support department. So we'll plug all the computers that belong to the support department into those ports. And then we'll designate another set of ports and create another VLAN for the accounting department. And finally, we'll designate another set of ports for another VLAN for the shipping department. And as you can see, the network traffic is separated between the departments because of the VLANs.
Sections
Laptop Components and Replacements
Laptops are portable computers with built-in displays and keyboards, powered by a rechargeable battery.
A laptop is a portable computer that has a built-in display and keyboard that you can take anywhere and use it just like a regular desktop computer. It also has a battery that supplies it with power. Typically, the battery can power the laptop for several hours depending upon what the laptop is doing. To charge the battery, the laptop will come with a battery charger that plugs into a wall outlet, which not only charges the battery, but also supplies the laptop with power.
Batteries and RAM can be replaced by shutting down the laptop, disconnecting power, and accessing the compartment or back cover.
But just like everything else, batteries get old and die after a certain period of time, and then you have to replace the battery. Now, replacing a laptop battery will vary slightly from different laptops, but generally speaking, the first thing you should do is to turn off the laptop and make sure that it's totally shut down, and then disconnect the power cord. Then, flip the laptop over and remove the battery compartment cover if it has one. Then, locate the slide release switches near the battery opening, slide the release switches to the release position and remove the battery. Then you just grab the new battery, align it correctly, and then slide it into place until it clicks and locks itself into place. There are also times when you might need to replace the RAM in the laptop or add more RAM. So, to do this, you need to turn off the laptop and unplug the power cord. And you should always refer to the owner's manual to find the specific procedure for accessing the RAM modules and where to find them because some laptops will have a small dedicated compartment door to easily access the RAM modules. But if it doesn't, then you have to remove the entire back cover to access the RAM. So whether you're accessing the RAM using the dedicated door or by removing the back cover totally, you should be able to see the RAM modules. The RAM modules are held in by clips on both sides of the module. So you would just push the clips outwards and then the module will tilt to a 45° angle. And then you just gently slide the RAM module out. Then grab the new RAM module. And you need to be sure to align the notches on the bottom of the RAM module with the slot in the laptop. Then you slide it in at a 45° angle, push it down flat until the clips automatically click and lock it into place.
Storage drives, keyboards, and wireless cards can be replaced, often requiring access via a dedicated door or the entire back cover.
Now, replacing a storage drive in a laptop is similar to replacing RAM modules because a laptop may also have a dedicated compartment door to easily access the storage drive. Or if it doesn't, then you have to remove the entire back cover. To remove the dedicated door, you would use a small Phillips screwdriver and then remove all the screws in the door. And then you will see the storage drive. The drive would also be held in by screws. So after you remove these screws, just gently slide the drive away from the SATA interface and remove it. Then just add the new drive and then reattach the door. There are also times when you might need to replace the keyboard in a laptop. So to do this, and just like everything else, be sure to turn the laptop off and unplug it. Now, some laptops will make this process easier than others. So, for example, some laptops may require you to remove the top bezel first, which requires you to use a prying tool such as a spudger to remove it. But other laptops will make it easier where the bezel doesn't have to be removed. So, for example, some keyboards are just held in place by clips around the keyboard. So, in this case, you can just use a prying tool or a tiny flathead screwdriver to unlock the clips and partially remove the keyboard. And then you have to disconnect the keyboard ribbon cable. And then you can fully remove the keyboard. Laptops will come with wireless cards such as Wi-Fi and Bluetooth. These will give the laptop the ability to communicate wirelessly using these technologies. But if you ever have to replace these cards, this is how you would do it. Now, some laptops will have a dedicated compartment door so you can easily access the wireless cards, such as with RAM or the storage drive. But if it doesn't, then you're going to have to remove the bottom cover. So, after you have spotted the wireless card, the first thing you need to do is to pop off the antenna wires with tweezers or your fingernails. Then you would just unscrew the old card with a small Phillips screwdriver and slide the card out of its slot. Then you would just get the new card, slide it into the slot, reinsert the screws, and tighten it down. And then reattach the antenna wires.
Replacing antenna cables is complex, requiring bezel removal and careful rerouting along the screen.
Now, if you ever have to replace the actual antenna cables themselves, then this requires a lot more work because the antenna cables are routed along the laptop's screen bezel. So, you're going to have to remove the top bezel on the laptop and the bezel surrounding the screen. Then, you would have to disconnect the antenna cables from the wireless card. Then you would have to carefully unroute the antenna cables from the laptop base and the screen.
Mobile Device Features and Connectivity
Built-in cameras and microphones facilitate video conferencing and online visual communication.
Mobile devices such as laptops, tablets, and smartphones may also have a built-in camera which is typically located above the screen. And they will also have a built-in microphone. The camera and microphone are mainly used for video conferencing and video calling over the internet. So two or more people anywhere in the world can visually communicate with each other if they have a camera and microphone on their device along with an internet connection.
Biometric devices like fingerprint scanners provide secure identity authentication through unique physical characteristics.
For authentication purposes, a mobile device may use biometrics to confirm an identity. A biometric device is used to prove the identity of a person by recognizing unique physical characteristics. So for example, a fingerprint scanner. Fingerprint scanners are used to read a user's fingerprint to prove authentication. You would just place or swipe your finger across the fingerprint scanner and then the scanner will either grant or deny you access based on your fingerprint. And other biometrics that can be used are facial recognition, retina scans, and voice patterns.
Wired connections commonly use USB, with USB-C being a modern, reversible standard for many devices.
There are several different options that you can use for making a connection to your mobile device. These include wired and wireless options. So, for example, let's say you wanted to connect your smartphone to your computer using a wire. And the most common wired connection is by using a USB cable. USB or universal serial bus will use several different interfaces. And today, a lot of modern smartphones will use the USB-C connection. The USB-C is a thin connector with rounded edges that easily plugs into a device because it doesn't have an up or down orientation, so it easily plugs in. And on the other end of the cable, you will find the host connection, which could be the standard rectangular USB-A connection, or if you have a modern computer with a USB-C port, then you can use a USB-C connection.
Older devices may use micro USB, mini USB, or Apple's proprietary Lightning port for wired connections.
Now, if you have an older smartphone, your device may use the micro USB or mini USB, and you can see the side-by-side difference between them. They are both approximately the same width, but the micro USB is about half its thickness. Or if you have an older iPhone, you might be using a lightning port connection. The lightning port is Apple's proprietary 8-pin connector. This connector easily plugs into a device because just like USB-C, it doesn't have an up or down orientation. The lightning connector is still being used today, but for new products, Apple has replaced it with USB-C.
NFC enables short-range wireless data sharing via direct tapping or proximity, without needing Bluetooth or Wi-Fi.
You can also make a connection to your smartphone using wireless options. And one way is by using NFC. NFC stands for near field communication. And this is a short range wireless technology that allows devices such as smartphones and payment devices to share data just by tapping or bringing them close to each other. So there is no need for using Bluetooth or Wi-Fi when using NFC.
Bluetooth is a short-range radio technology for connecting devices, operating at 2.4 GHz with speeds up to 24 Mbps and a 100m range.
And another option is by using Bluetooth. Bluetooth is a short range radio that provides a way to connect and exchange information between devices such as laptops, phones, and tablets. It operates at 2.4 GHz and is capable of transmitting both voice and data. The latest standard of Bluetooth has a transfer speed of 24 megabits per second and has a maximum range of approximately 100 meters.
Hotspot tethering transforms a smartphone into a Wi-Fi access point using its cellular connection.
And another wireless option is by creating a hotspot using tethering. Smartphones get their internet access using cellular networks. And you can transform your smartphone into a wireless access point so it can share its internet connection with your other devices. Most smartphones would have the option of creating a hotspot at the touch of a button. And then once the hotspot is turned on, your phone will broadcast a Wi-Fi signal just like a Wi-Fi router or a wireless access point so that nearby devices can connect to its signal and access the internet from the smartphone's cellular network.
Styluses, used for drawing or writing on mobile devices, connect via Bluetooth.
There are also different accessories that you can use to connect to your mobile device, and one of them is a stylus. A stylus is a pen-like battery powered device that's used on mobile devices instead of your finger. You can use a stylus to draw images, open applications, or write something. And you connect the stylus to your device by using Bluetooth.
Headsets, with integrated headphones and microphones, offer hands-free communication and can connect wired or wirelessly.
And another accessory that you can connect to your device is a headset. A headset is a set of headphones along with a microphone in one unit. These provide a hands-free way of communicating with other people either on the phone, in meetings, or online gaming. And you can connect a headset to your device either wired or wirelessly. To connect using a wire, you can use a USB connection. Or another wire connection is by using the standard 3.5 mm jacks where on one end you would have two jacks, a green and a pink. And these will plug into your computer into the audio and microphone ports respectively. Or you can also connect a headset wirelessly using Bluetooth. Now these will come in the standard form factor here. Or you can also use something like AirPods. AirPods which are made by Apple are significantly smaller than a traditional headset that are placed in the ear rather than over them.
External speakers connect via 3.5mm jack, USB-C, or Bluetooth, offering improved sound over built-in phone speakers.
Speakers are another accessory that you can connect to your mobile device. Speakers can be attached by using the standard 3.5 mm jack, USB-C, or they can be attached wirelessly by using Bluetooth. Pairing Bluetooth speakers to a device such as a smartphone will produce a louder and better sound rather than relying on the speakers built into a smartphone.
Webcams, often built-in, capture video/images for conferencing and can include microphones; external ones connect via USB.
A webcam is a device that's used for capturing video and images. Webcams are mainly used for video conferencing and video calling over the internet. A lot of modern devices will already have a built-in webcam, but if your device doesn't have one, you can attach an external webcam and connect it using a USB connection. And most webcams will also have a built-in microphone to capture audio as well.
Docking stations convert laptops into desktop-like setups by connecting external monitors, keyboards, and other peripherals.
A docking station is used for laptop computers. It's a device that is used for basically turning your laptop into virtually a desktop computer. We all know that laptops are generally smaller than desktops. So for example, on a laptop, the monitor and keyboard are generally small. So, if you wanted to use your laptop at your desk and you wanted to use a bigger monitor and keyboard, you can simply set the laptop in the docking station and it will automatically connect to them and use them depending on what is already plugged into the docking station, whether it's a monitor, keyboard, mouse, printer, and so on. So, a docking station eliminates the hassle of connecting all these individually. You just simply attach and then start using them instantly.
Port replicators extend a device's connectivity with additional ports like USB, Ethernet, and video outputs, especially useful for laptops.
A port replicator is a USB external device that you can attach to your device. The replicator will have extra ports such as USB, Ethernet, and video to give your device extra ports for devices to connect to. So, for example, this port replicator has USB, HDMI, DisplayPort, and an Ethernet port. A port replicator is especially useful on laptop computers because laptops won't have as many ports compared to desktop computers.
Trackpads control cursors using finger movements and multi-touch gestures, serving as a built-in mouse alternative on laptops.
For space saving and convenience, laptop computers will use a trackpad instead of a mouse. A trackpad is a flat surface on a laptop that is used for controlling the cursor using your finger. It turns finger movements into multi-touch gestures that replaces everything that a standard mouse can do. Now, if your device, such as a desktop computer, doesn't have a trackpad, but you desire to use one, you can always attach an external trackpad. These will be attached using a USB connection or a wireless connection using Bluetooth.
Digitizers convert analog drawings into digital formats on a computer, typically connecting via USB or Bluetooth.
A digitizer is a device that is used to convert analog movement such as a hand drawing and convert it into a digital form on your computer. It'll have a flat surface like a tablet along with a stylus. And as you draw on the flat surface using the stylus, it'll record the image from the stylus and process the drawing on your computer screen. A digitizer typically connects to your computer using a USB cable or Bluetooth.
Cellular connections (3G, 4G, 5G) enable smartphones to make calls and access the internet via cell towers.
Smartphones can make phone calls and access the internet by the use of cellular towers. And it's through these towers that cellular connections like 3G, 4G, and 5G are made. Cellular carriers depend on these towers to send and receive voice and data between phones and the main network. Cellular data can also be turned on or off on your smartphone. When you buy a smartphone from a carrier, cellular data will be turned on by default. But for some reason, if you ever need to turn off your cellular data, whether it's to save battery or minimize data usage, you can turn it off in your device's network settings. Or another way to turn off cellular data is to turn on airplane mode. Airplane mode stops all wireless signals on your phone, including cellular, Wi-Fi, and Bluetooth.
Hotspot configuration involves setting an SSID (network name) and password for devices to connect to the smartphone's internet.
Now, as I stated earlier, most smartphones will have the option of creating a hotspot at the touch of a button. And then once the hotspot is turned on, your phone will broadcast a Wi-Fi signal just like a Wi-Fi router or an access point. To configure the hotspot, you need to go into the hotspot's configuration settings. And from here, you can give your hotspot an SSID, which is the name of your hotspot network. So, we'll call it "my hotspot" and then we'll give it a password. So, now when other nearby devices scan for Wi-Fi networks, it'll display the hotspot's name in the Wi-Fi list and then all they would have to do is click on the name, type in the password, and then they'll be connected.
Using Wi-Fi instead of cellular data can save money, conserve battery, or provide faster speeds.
So, as we just discussed, smartphones use cellular data to make phone calls and access data. But smartphones will also have the ability to do the same thing by using Wi-Fi instead. Now, the reasons for using Wi-Fi instead of cellular data will be things such as saving money and data, which depends on the data plan from the carrier. It could also be to save battery life or depending upon your location, the Wi-Fi speed may be faster than cellular in that area.
Enabling Wi-Fi on a phone involves going to settings, scanning for networks, selecting one, and entering a password if required.
To turn on Wi-Fi on your phone, you need to go into your device settings and enable Wi-Fi. And then once it's enabled, your phone will scan for Wi-Fi signals that's in range of your phone. Then you can select a Wi-Fi network from the list and join it. But if the Wi-Fi network requires a password, then you need to enter the password for it.
A SIM card or eSIM is required for a smartphone to connect to a cellular network, providing identification and service.
In order for a smartphone to connect to a cellular network, it requires a SIM card. A SIM or subscriber identity module card is a small chip that uniquely identifies you and gives your phone access to a cellular network. It contains a unique identification number, your phone number, your contacts, and your cellular plan. It's a physical card that can be inserted or removed. And there is also an eSIM. An eSIM or embedded SIM is a digital SIM card that is embedded in the phone's hardware. So, there's no physical card. So, instead of inserting or removing a physical SIM, an eSIM can be added and activated by using an app or by scanning a QR code. And it can also be easily deleted. And other benefits of an eSIM is that it can't be removed or stolen, such as in the case of a regular SIM. And you can also put multiple profiles on an eSIM that can store different network profiles that you can switch to easily.
Bluetooth pairing involves powering on devices, enabling Bluetooth, and selecting the device from a list, sometimes with a PIN.
Another feature that you can find on a smartphone is Bluetooth. And you can use Bluetooth to connect or pair certain devices such as headsets, earbuds, and speakers to your device, such as a smartphone. So, as an example, let's say that you wanted to pair earbuds to your smartphone. So, the first thing you need to do is to power on the earbuds and then put them in pairing mode. To turn on pairing mode, you need to see the specific instruction for the earbuds on how to do this. But typically, this is done by holding down its power button or Bluetooth button until you see a light flashing, which indicates it's now in pairing mode. Then you need to enable Bluetooth on your smartphone. And this is done by going to the settings and enable Bluetooth. Then in the list of available Bluetooth devices that appear, you should see the earbuds in the list. Then you would just click on earbuds, type in the four digit pin code if it requires you to, and then you are paired.
Location services use GPS (satellites) or cellular (cell towers) to determine a device's global position.
Your smartphone will have location services that can locate your device anywhere in the world. And it can do this in a couple of different ways. It can do it by using GPS or cellular. And the difference is that GPS uses satellites and cellular uses cell towers. Now GPS stands for global positioning system. A GPS works by locating your device using satellites orbiting the earth. And it uses a technique known as trilateration. Trilateration uses satellites, ground stations, and a GPS receiver on your phone to calculate certain distances. and it uses these calculated distances to determine your precise location. Now, cellular can also be used to locate your device. But instead of calculating your distance from satellites, cellular calculates your location by analyzing the signal strength and distance from your smartphone to cell towers. And it can use multiple towers to triangulate the signals to get a more accurate location.
MDM systems centrally manage and secure employee mobile devices for organizations.
If an organization has a lot of employees, those employees will also each have a device such as a laptop, tablet, or smartphone within the organization. And for security purposes, these devices need to be safely managed to ensure safety to an organization. And this is why an organization would use a third-party solution called a mobile device management system or MDM. An MDM allows administrators to manage mobile devices from a centralized location. The MDM allows for an administrator to configure, manage, update, or even lock a device remotely if the device is stolen or lost. It could also enforce different policies such as what app such as a camera can be used or not.
BYOD (Bring Your Own Device) policies allow employees to use personal devices for work, saving costs but creating security risks.
Employees who bring their own network devices such as smartphones, tablets, or laptops and use them for job-related tasks can use it through a program called BYOD or bring your own device. This policy can save an organization money because they wouldn't have to purchase and maintain these items for their employees. However, it could create a security risk. For example, if the employee devices have malware installed.
CYOD (Choose Your Own Device) and COPE (Corporate Owned Personally Enabled) are alternative device management policies for businesses.
If an organization allows employees to bring their own device to work, but the organization creates a list of only approved devices that the employees can choose from, then this is a policy called CYOD or choose your own device. And if an organization pays and therefore owns the devices for the employees to use then this policy is known as COPE or corporate owned personally enabled.
Synchronization ensures data accessibility across devices and provides redundancy, typically using cloud services.
If someone wants to synchronize the data of a mobile device to another location for the purpose of accessing that information on any device then this is known as synchronization. Synchronization provides assurance that if a mobile device is missing, the exact data will remain accessible on another system when setting up a new mobile device. And it also provides redundancy. Some things that someone would want to synchronize are things such as files and folders, calendars, contacts, photos, videos, music, and so on. And a lot of smartphones will have a setting where you can select which type of data on the phone that you want to sync. Synchronization is typically done using the cloud, which basically means that the data is stored on the server out on the internet. Some popular cloud services that will be used for synchronization are Dropbox, Google Drive, Apple's iCloud, and Microsoft's One Drive. If you're using email such as Gmail, Apple Mail or MS Outlook, these email providers are synchronized by default. The email is not necessarily stored on your device, but it's actually stored in the cloud. So, this is why you are able to access your email from anywhere in the world by logging into your email account from any device.
Networking Protocols and Standards
Network ports are logical connections with unique numbers (0-65535) for program communication.
Now a port is a logical connection that is used by programs to exchange information and these ports have a unique number that identifies them. The number ranges from 0 to 65535 but for the exam you only need to know a few of them. So here is a chart of the ports that you need to know for the exam. Some of these ports are very common and are used every single day such as port 80 which is used for bringing up web pages on the internet. And another one is port 443 which is used for loading up secure web pages. And another common port is port 25 and this is used for sending email.
TCP ensures reliable, ordered data delivery through a connection-oriented, three-way handshake, resending lost packets.
Whenever a computer wants to communicate with another computer, the communication between those two computers needs to be good and reliable so it can guarantee that the data is received correctly. For example, when you want to view a web page or download a file or look at an email, you'd expect to view the web page intact and in order with nothing missing. or if you're downloading a file, you would want the entire file and not just a part of the file because if data is missing or out of order, then it wouldn't be of any benefit to you. So, this is where TCP comes in. TCP stands for transmission control protocol and this is one of the main protocols used in a TCP/IP network and TCP is what is used to guarantee that all the data is received and in order because without TCP then some of the data could be missing or out of order because if you view a web page without TCP your web page could be all messed up. The images could be missing or the text could be backwards and out of order or if you download a file then you might not get the entire file or you could get the file out of order which would render the file useless. So again this is where TCP comes in. Now TCP is a connection-oriented protocol which basically means that it must first acknowledge a session between the two computers that are communicating. So the two computers verify a connection before any communication takes place. And it does this by using a three-way handshake. So the first step is that a computer will send a message called a SYN. Then the receiving computer will send back an acknowledgement message telling the sender that it has received the message. And then finally the sender computer sends another acknowledgement message back to the receiver. And then once this has taken place, data can be delivered. Another important thing to remember about TCP is that it guarantees the delivery of the data. So if a data packet goes astray and doesn't arrive then TCP will resend it.
UDP is a faster, connectionless protocol that prioritizes speed over guaranteed delivery, often called 'fire and forget'.
Now UDP is very similar to TCP. UDP is also for sending and receiving data but the main difference is that UDP is connectionless which means that it does not establish a session and it does not guarantee data delivery. So when a computer sends their data, it doesn't really care if the data is received at the other end. And that's why UDP is known as the fire and forget protocol because it sends data and it doesn't really care what happens to it as this demonstration will show. Another point to remember is because of the less overhead that's involved of not guaranteeing data delivery, UDP is faster than TCP.
Wi-Fi standards (IEEE 802.11) have evolved significantly since 1997, increasing speed and capabilities.
Now, Wi-Fi is a wireless technology that uses radio waves that allows networking devices the ability to communicate with other networking devices wirelessly using a device such as a Wi-Fi router or a wireless access point. And since the first development of Wi-Fi, there has been some significant changes in the technology and speed and the Wi-Fi standards. Now the organization that created and maintains the wireless standards is called the IEEE which stands for the Institute of Electrical and Electronics Engineers and they are responsible for starting a project called the 802 project and the wireless standards that they created was called and started with the number 802.11. So here is a chart of the different 802.11 wireless standards that have been released throughout the years. It shows their generation name, maximum speed, frequencies, and release year. Starting with the first wireless standard, which was 802.11, which came out in 1997, and all the way up to the latest standard, which is the 802.11be standard, which was released in 2024.
Wi-Fi uses 2.4 GHz, 5 GHz, and 6 GHz bands, each with trade-offs in range, speed, and interference levels.
Wi-Fi uses three frequency bands. These are the 2.4 GHz, 5 GHz, and 6 GHz. And each of these bands has its own advantages and disadvantages. Now, the 2.4 GHz band has the longest range of the three bands, but it's also very common and is used in a lot of other devices such as microwave ovens, cordless phones, wireless cameras, and so on. So, a lot of times these devices will interfere with other Wi-Fi signals and this could cause problems because it would slow down the Wi-Fi network speed and sometimes could cause you to lose connection to the Wi-Fi router and it's also the slowest band. The 5 GHz band is faster than the 2.4 and it's also not as common. So there's a lot less interference and more privacy with the 5 GHz band. However, the disadvantage is that it has a shorter range than the 2.4. And the newest band is the 6 GHz band. The 6 GHz band is the fastest of the three bands. And since it's relatively new, it has the lowest interference because few devices use it. But the disadvantage is that it has the shortest range of the three.
Wi-Fi channels within bands, measured in MHz, allow data transfer; non-overlapping channels (e.g., 1, 6, 11 in 2.4 GHz) minimize interference.
Now in all these frequency bands are Wi-Fi channels. These channels are smaller ranges of the frequencies in a band. And devices use these channels to send and receive data. These channels have different bandwidths and are measured in hertz such as 20, 40, 80, and 160 megahertz. The wider the channel, the more data can be transferred. And you can also use these wireless channels to fine-tune and alter a frequency because sometimes you might need to change to a different channel if you are experiencing any interference from other nearby wireless networks. So for example, the 2.4 GHz band has 11 channels to choose from, but of these 11 channels, only three are non-over overlapping, such as channel 1, 6, and 11. So, if you're experiencing interference with other Wi-Fi networks, you can try changing the channel to one of these non-over overlapping channels.
Bluetooth creates low-power, short-range wireless connections for device pairing and information exchange.
Bluetooth is a low power wireless technology that uses a short range radio that provides a way to connect nearby devices to each other. Bluetooth devices will have a computer chip inside of them that will broadcast a signal so that other Bluetooth devices can connect to them which is known as pairing. And when the devices are paired, they will then be able to exchange information between them.
RFID uses electromagnetic fields to track and identify objects wirelessly, functioning like a wireless barcode.
And RFID stands for radio frequency identification. And this is a wireless technology that uses electromagnetic fields to track and identify tags attached to objects. It functions similar to a wireless barcode that can be scanned without a direct line of sight.
NFC is a short-range wireless technology for data sharing via simple tapping or proximity.
NFC stands for near field communication. And this is a short range wireless technology that allows devices such as smartphones and payment devices to share data just by tapping or bringing them close to each other. So there is no need for using Bluetooth or Wi-Fi when using NFC.
A server is a central computer providing services (file sharing, databases, web hosting, email) to multiple clients.
A server is a dedicated computer that provides services on behalf of clients such as ordinary desktop computers or workstations. It's a centralized machine where multiple clients connect to either over the internet or in a local area network and they connect to a server for a specific service or role that the server provides. So for example, a server may take the role of a file share. File sharing is when the server acts as a centralized computer that stores files and then these files can be accessed and shared over a network to clients that connect to that server. And a database is another type of server. This is a type of server that stores data on the back end and then that data is retrieved from computers on the front end using queries such as SQL. And a server can also act as a web server. A web server is a server that stores website data such as HTML code, videos, images, and so on and makes it available to anyone who wants to view the web page. So when someone wants to view a certain website, they would type in the address of the website in their web browser such as example.com and then it would connect to the specific web server that's hosting that website and then the web page would appear on their device. A server can also act as a mail server. A mail server is a server that manages email. It manages, sends, and receives email on behalf of clients. So for example, when someone sends you an email, that email goes from their device to the mail server. And then for the other person to retrieve the email, they would use their device to access the email server to retrieve and view the email.
A print server manages print jobs over a network, acting as a central hub for multiple devices and printers.
A print server is a software application or a hardware device that manages print jobs over a network. It acts as a centralized hub that receives print jobs from network devices and sends them to the printer. A print server can be software built into a modern network printer or it can be a standalone device. So for example, a regular desktop computer can also act as a print server and this is when a printer is directly connected to a computer using a USB cable and then that printer can be configured as a network share. So other devices on the same network can access the printer. So this computer here is now a print server because it's acting as a middleman managing all the print jobs between the printer and the other devices on the network.
Log aggregation centralizes log data from various sources for easier analysis and system monitoring.
Log aggregation is the act of collecting and organizing log data from several sources into one place. This makes it easy to analyze, fix, and keep an eye on systems and applications. But without log aggregation, network administrators would have to go through log files from many different sources manually, which could take a long time and be inefficient. And many systems and applications use syslog as a standard logging protocol. Syslog works by using a centralized syslog server or collector. This server receives syslog messages from many different devices such as routers, switches, servers and applications. Syslog messages inform network administrators about activity, security incidents and application issues which helps them to keep an eye on, fix and keep their systems running smoothly.
AAA (Authentication, Authorization, Accounting) is a security system controlling access and auditing resource usage.
AAA stands for authentication, authorization, and accounting. And this is a security system that controls access to computer resources, enforcing policies and auditing usage. It is used to manage who can access the network, which is authentication, what they can do, which is authorization, and to keep track of their activity, which is known as accounting. These protocols include radius, TACACS+, and diameter.
NTP synchronizes computer clocks with master clocks using periodic requests to ensure time accuracy.
NTP stands for network time protocol and this is an internet standard that is used to synchronize the clocks of computers with the US naval observatory master clocks. This protocol runs on each computer and it sends out periodic requests to the server to make sure the time is in sync.
A spam gateway filters incoming email, blocking unsolicited messages before they reach the email server.
A spam gateway is a security barrier that is positioned between your email server and the internet. So, as email comes in, it'll determine which email is legit and which email is spam. And any email that it detects as spam will be blocked.
Unified Threat Management (UTM) integrates multiple security features into a single system for streamlined network defense.
An all-in-one IT security strategy called unified threat management or UTM combines several security features including web filtering, intrusion protection, firewalls, and antivirus software into a single system. It lowers expenses and streamlines network defense, especially for small to medium-sized businesses.
SCADA, ICS, and OT systems control and monitor industrial equipment in real-time for efficiency and problem detection.
SCADA, ICS, and OT are similar terms that describe systems that are used for controlling and monitoring equipment that are used in industrial facilities such as power plants, water treatment plants, and refineries. These systems communicate with sensors and systems in real time that are out in these industrial facilities. And those sensors and systems send back information to PLCs and RTUs which then sends it to the SCADA computers to be analyzed. And this information could be things like how to reduce waste, how to improve efficiency or if there are any problems.
IoT connects everyday devices, while IIoT connects industrial machinery and processes for specific operational purposes.
The industrial internet of things and the internet of things are both networks of devices that are linked together, but they are used for different things and have different areas of coverage. Internet of things is the network of everyday devices that are connected to the internet such as the things that the common person would use such as smart devices. But the industrial internet of things on the other hand is a network of connected industrial devices and processes such as machinery, transportation, energy and so on.
IP Addressing and Configuration
DHCP automatically assigns IP addresses and network configuration details to devices on a network.
DHCP stands for dynamic host configuration protocol. Now, every computer or device on the network has to have an IP address for communication purposes. And there are two ways that a computer can be assigned an IP address. It could be done by using a static IP or a dynamic IP. Now, a static IP is where a user assigns a computer or device with an IP address manually. Now, this was the original method that was done in the beginning of networking. So for each computer on the network, you had to open up the computer's network configuration page and manually type in an IP address. But in addition to an IP address, you also had to type in the subnet mask, default gateway, and a DNS server. But there is a better and easier way to assign a computer an IP address, and this is called a dynamic IP. A dynamic IP is where a computer gets an IP address automatically from a DHCP server. A DHCP server automatically assigns a computer with an IP address. And in addition to an IP address, it can also assign a subnet mask, default gateway, and a DNS server. Now, a DHCP server assigns IP addresses to computers on the network from its scope. A scope is a range of consecutive IP addresses that a DHCP server can hand out. So for example, here we see a scope of IP addresses from this DHCP server. So as you can see, this range starts with this IP address and ends with this IP address. So computers and devices on this network will get an IP address from this range of IP addresses. So this scope can give out 100 IP addresses.
DHCP reservations ensure specific devices always receive the same IP address, identified by their MAC address.
Now if you want a computer or device on your network to have a specific IP address all the time, in other words, you never want that IP address to change, you can create a reservation on the DHCP server. A reservation ensures that a specific computer or device identified by its MAC address will always be given the same IP address when that computer or device requests an IP address from the DHCP server. So for example, if I create a reservation for my computer, the DHCP server will recognize my MAC address and will always give me this specific IP address. Now, reservations are not typically given to regular computers. They are typically given to special devices such as network printers, servers, and routers that require using the same IP address constantly.
DHCP exclusion reserves IP addresses or ranges for devices that use static IPs, preventing conflicts.
Now, DHCP exclusion is an IP address or range of IP addresses that the DHCP server does not give out. These IP addresses are reserved for devices that use them as static IP addresses. So the difference between reservation and exclusion is that reservation is reserving dynamic IP addresses while exclusion is for excluding static IP addresses.
DHCP leases assign IP addresses for a limited time, automatically renewing to maintain connectivity.
When computers obtain an IP address from a DHCP server, the server assigns the IP address as a lease. So the computers don't actually own the IP address. It's actually a lease. And a lease is the amount of time an IP address is assigned to a computer. So for example, if I do an IP config/all in a command prompt in a Windows computer, you can see that the DHCP service has assigned my computer an IP address with a lease of one day. Now, typically a DHCP server will automatically renew the IP address for you. So, you won't have to do anything or even notice that the IP address is being renewed. You can just continue on like normal and go about your business.
APIPA (Automatic Private IP Addressing) allows Windows devices to self-assign an IP address (169.254.x.x) when a DHCP server is unreachable.
Every computer has to have an IP address to communicate on a network. Now, when a computer is set to automatically obtain an IP address, it gets the IP from a DHCP server. But what happens if a computer cannot reach a server? So for example, what happens if the DHCP server goes down or if the connection to the server is lost? Well, if this happens, then the computers that are running Microsoft Windows, the computers themselves will self assign their own IP address. These IP addresses will be in the range starting with 169.254.0.1. And this type of self assigned IP addressing is what's called APIPA or automatic private IP addressing. And in addition, they will also assign themselves a 16-bit subnet mask. And the reason why computers do this is that even though they can't get an IP from a DHCP server, they will still be able to communicate with other computers on the same local network or subnet that also have self assigned IP addresses.
SLAAC (Stateless Address Auto Configuration) enables IPv6 devices to auto-configure IP addresses using router advertisements and MAC addresses.
Now, similar to APIPA that's used in IP version 4 networks, there's also SLAAC that's used in IP version 6 networks. And SLAAC stands for stateless address auto configuration. This feature is built into IP version 6 and this allows IP version 6 devices to autoconfigure their own IP address and it works by using router advertisements or RAS and using the devices MAC address. One of the main differences between APIPA and SLAAC is routability. APIPA IP addresses are not routable. So the devices can't communicate outside their own network. But SLAAC IP addresses are routable and they can talk outside their own network. And another difference is that where APIPA is a backup method, SLAAC is actually the preferred way for assigning IP version 6 addresses.
IPv4 addresses are 32-bit numeric addresses, divided into public (internet access) and private (internal use) ranges.
An IP address is a numeric address. It's an identifier for every computer or device on a network. Every device has to have an IP address for communication purposes. Now, this is an IP version 4 address. An IP version 4 address is a 32-bit numeric address written as four numbers separated by periods. And each group of numbers that are separated by periods is called an octet. Now we're going to discuss the difference between public and private IP version 4 addresses. Now when you order internet service from a company, they are going to assign the modem in your home or business a public IP address. This public IP address is registered on the internet. It's what gives you access to the worldwide web. So if you don't have a public IP, you cannot access the internet. Public IP addresses are unique. So there are no duplicates of public IP addresses. Now when IP addresses were created, engineers didn't realize how big the internet would become because even though there were over 4 billion IP version 4 addresses available, the engineers thought that this would be enough, but they were obviously wrong because of the explosive growth of the internet. So, in order to prevent a shortage of public IP version 4 addresses, engineers from the Internet Engineering Task Force in a document labeled RFC 1918 developed private IP addresses. Now, private IP addresses are not publicly registered on the internet. So, you can't access the internet using a private IP address. But if your device has a private IP address and you want to access the internet, your private IP has to be converted into a public IP address before you can access the internet. Private IP addresses are only used internally such as inside a home or a business. They are not used out on the public internet. And the service that converts or translates this is called NAT or network address translation. And this is a service that's built into a router. So not only does it translate private to public, but it also translates public to private. Because if a computer on the internet wants to communicate with a computer on this private network, the public IP address needs to be translated by NAT to the private IP address for that computer.
Private IPv4 addresses (RFC 1918 ranges: 10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x) are used internally and translated to public IPs via NAT.
The RFC 1918 standard created private IP addressing to prevent a shortage of public IP addresses available to ISPs and subscribers. Private IP addresses have three different classes and these classes have different ranges. A class A private IP starts with the number 10. This class is typically used for large organizations. Class B starts with 172 and this is used in medium-sized organizations. And class C will start with 192 and this is used for small organizations or homes.
IPv6 addresses are 128-bit hexadecimal addresses, vastly increasing the number of available IP addresses compared to IPv4.
When the internet was first being developed, programmers didn't realize how big it would become. They thought that IP version 4, which produced over 4 billion IP addresses, would be enough. But they were obviously wrong. IP version 6 is the next generation of IP addresses. The main difference between IP version 4 and IP version 6 is the length of the address. The IP version 4 address is a 32-bit numeric address whereas IP version 6 is a 128-bit hexadecimal address. Hexadecimal uses both numbers and alphabets in the address. So with this type of address, IP version 6 can produce an unbelievable 340 undecillion IP addresses. That's the number 340 with 36 digits after it. So as you might have guessed, IP version 6 is more than enough for the foreseeable future.
A proxy server acts as an intermediary, forwarding client requests to the internet and returning responses, offering security, anonymity, and caching.
Now the definition of a proxy is just someone or something that has authority to do something for another person or thing. So in terms of computers and networks, a proxy is a server and a proxy server acts on behalf of clients on a network such as retrieving data for those clients. A proxy is a middleman that sits between a private network and the public internet. So for example, here we have a private network with a bunch of computers or clients. Now all of these computers have access to the internet. But as most of us know, with all these computers having the ability to access the internet, it could also create a massive security concern. Because with all of these individual computers accessing the internet, they could draw in malicious traffic that could wreck havoc inside this network. So this is where a proxy or to be more specific, a forward proxy can be beneficial. When a forward proxy server is used on this network, the proxy server is now the guardian of this network. So when all of these computers want to access the internet, they go to the proxy server instead. and then the proxy server will fetch the data out on the internet on their behalf. So by doing this this creates a safety barrier between a private network and the internet because a major benefit of a proxy is that it can regulate traffic by blocking harmful websites. And some other benefits of a proxy is that it hides the identity of clients by masking their IP addresses and using its own IP address. So when these clients connect to websites and servers out on the internet, those websites and servers only see the IP address of the proxy server and not the clients. Another benefit is that it logs user activity. A lot of organizations like to know what websites that their clients are visiting and by using a proxy, it will keep track of the websites that were visited and how long they were on those websites. And another benefit is that it can bypass restricted content. Some organizations like schools and governments may restrict access to certain websites, but by using a proxy, you may be able to bypass those restrictions and access those restricted websites. And finally, another benefit of using a proxy server is speed because a proxy can cache or store copies of websites that are frequently used by their clients. So instead of the proxy server fetching the same websites out on the internet over and over again, those websites can be stored in the proxy's cache database instead.
VPNs create secure, encrypted tunnels over public networks, protecting data and masking IP addresses for anonymity.
Now VPN stands for virtual private network. A VPN is what establishes a secure and reliable network connection over an unsecured network such as the internet. It protects your internet activity and disguises your identity as you surf the internet. So for example, when you order internet service from your ISP or internet service provider, they will set up your internet connection. And when your setup is complete, your internet activity is routed through your ISP servers, which means that your ISP can see and log all of your internet activity. so they can see every website that you visited. Now, typically this wouldn't be a problem if they kept your internet activity private. However, there is a possibility that your ISP could share your information with other third parties such as advertisers or maybe even the government. And if this were to happen, your internet activity is no longer private. But by using a VPN, your online activity will bypass your ISP server and will be redirected to another server, which is a VPN server, which means that your internet provider or any other party can no longer see what websites you are visiting. The VPN server is now your source where all of your internet activity goes through. And this has several benefits. And the first benefit is that a VPN will disguise your identity by hiding your IP address. Whenever you order internet service from a provider, they will assign you an IP address. That unique IP address is attached to your home or business. So whenever you visit a website, that website can see your IP address. But when using a VPN, websites can no longer see your IP address. They now only see the IP address of the VPN server, which effectively hides your identity, so you can surf the internet anonymously. Another benefit is that a VPN will encrypt and protect your internet data. Whenever you go on the internet, the data that you send and receive is broken down into a bunch of smaller data packets. These data packets travel across the public internet and ultimately find their way to their destination. But as they are traveling across the internet, your data can be viewed by ISPs, governments, and it can also be intercepted by hackers, especially if you use public Wi-Fi networks. But a VPN will prevent this. A VPN will encapsulate each data packet by adding an extra layer of protection to each one, which is known as tunneling. This extra layer adds a layer of protection to ensure your data is secure and kept private as it travels across the internet in a virtual tunnel. So any activity that you do on the internet such as visiting web pages or transferring files, the data is encrypted and kept private when using a VPN.
VLANs logically group network devices into separate segments, enhancing security and traffic management regardless of physical location.
VLAN stands for virtual local area network. A VLAN is a local area network where computers, servers, and other network devices are logically connected regardless of their physical location. So even if these devices are scattered in different places, it wouldn't matter because a VLAN can logically group them into separate network segments. And the purpose of a VLAN is for improved security, traffic management, and to make a network more simple. So, as an example, let's say that you have a three story office building and in this building you have computers that belong to certain departments that are mixed in with other computers that belong to other departments on the same floor. So, the red computers represent the accounting department, the blue computers represent the shipping department, and the green computers represent the support department. Now, as you can see, all these computers from these different departments are all connected to a switch, and they are all on one segment on a local area network or LAN. So, all the network broadcast traffic from the different departments are mixed in with other departments. So, the departments are all seeing each other's network traffic. Now suppose as a network administrator you wanted to separate the network broadcast traffic between these departments from each other, so that the accounting department doesn't see any traffic from support, support doesn't see any traffic from shipping and so on. Now, one way to solve this is to physically move the computers that belong to the same department and put them together, such as putting them on the same floor and deploying extra network hardware and cabling. But this could be a hassle and unnecessary work. But there is an easier way to accomplish this and that way is by creating VLANs. By using VLANs on a VLAN capable switch, you can logically create several virtual networks to separate the network broadcast traffic. So in this case, we're going to create three VLANs for three different departments. So we're going to create a VLAN for the accounting department and then create another VLAN for the support department and then create another one for the shipping department. So now as the VLANs are implemented the traffic between the three departments are isolated. So they won't see any traffic created by the other departments. They only see their own network traffic even though all the computers from the different departments are connected to the same switch. So in our example, the VLANs were created on the switch. And this is done by designating specific ports on the switch and assigning those ports to a specific VLAN. So on the switch, we'll create a VLAN for the support department. So we'll plug all the computers that belong to the support department into those ports. And then we'll designate another set of ports and create another VLAN for the accounting department. And finally, we'll designate another set of ports for another VLAN for the shipping department. And as you can see, the network traffic is separated between the departments because of the VLANs.
DNS, Network Devices, and Security
DNS resolves domain names to IP addresses through a hierarchy of root, TLD, and authoritative name servers.
In this section, we're going to be talking about DNS and DNS records. DNS stands for domain name system and the most basic job of DNS is to resolve domain names to IP addresses. And the reason it has to do this is because computers don't understand names. They only understand numbers. A domain name is just a text that you type in a web browser when you want to go to a certain website such as example.com, google.com, yahoo.com and so on. So when you type in a domain name such as example.com in a web browser, DNS will resolve that domain name into an IP address so you can retrieve the website. Now in a DNS hierarchy, there are three main levels of servers. There are the root servers, the top level domain servers and the authoritative name servers. But of these three, the DNS servers that are responsible for storing the DNS records for resolving domain names to IP addresses are the authoritative name servers because they are responsible for knowing everything about the domain name, including the IP addresses and much more. But in order for your query to resolve example.com into an IP address, it needs to know which name server to ask. So in order to find the correct name server, the query must first go through the top of the DNS hierarchy which is the root server. And once it reaches the root server, the root server will look at example.com and will forward the query to the correct top level domain server. The top level domain server is responsible for information of the top level domains such as .com, .net, .org, and so on. So in this case the root server will forward the query to the .com top level domain server because the top level domain for example.com is.com and then the top level domain server will forward the query to the specific authoritative name server that's responsible for the example.com domain and once the query reaches the name server, example.com will be resolved to the IP address so the website can be retrieved.
Common DNS records include A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail server), and TXT (text/verification).
So in a DNS database, you have what's called a DNS zone file. And this file contains the DNS records. Now, there are numerous DNS records, but I'm only going to talk about the most common ones. So the first DNS record is the A record or address record. And this is the most common DNS record. This is what resolves a domain name to an IP address. To be specific, it resolves to an IP version 4 address, which is a 32-bit numeric address. So, in the example we just did earlier, when you type in a domain name such as example.com in a web browser, the A record is what DNS uses to resolve a domain name to an IP address. And then we also have the TTL or time to live. This field tells us how long each record is valid until the next update. And then there's also the quad A record. And this record is just like the A record. So both A and AAAA records resolve domain names to IP addresses. But the difference is that AAAA records resolve domain names to IP version 6 addresses. An IP version 6 address is a 128-bit alpha numeric address that's replacing the older IP version 4 addresses. The next DNS record is called CNAME or canonical name. And what this does is that it resolves a domain or subdomain to another domain name. So basically, it's an alias for another domain name. So as an example, computers read domain names from right to left. And domain names will have several parts. A root domain, a top level domain, a second level domain, and a subdomain. So when we look at example.com there is also a hidden dot right after com even though it's hidden and we don't see it but that dot is the root domain. The .com is the top level domain and example is the second level domain. But if there is an additional name to the left of a second level domain then that would be a subdomain. So for example, www is a common subdomain, which is why it is common to create a CNAME record pointing www.example.com to example.com. Which is why when you type example.com or www.example.com in your web browser, you'll end up at the same .com website because of that CNAME record. Subdomains are also often used when a website has different services running on the same server and are using the same IP address. So as an example, let's say that example.com has an FTP service running on the same server as their website. So in this case, they can create a subdomain such as FTP.example.com for example.com for their FTP service on the server and then they can create a CNAME record and have it directed to example.com. So now when users type in FTP.example.com in their web browser, DNS will look at the CNAME record and forward the users to example.com. Now even though it's pointing to example.com, but once the request reaches the web server the web server will inspect the URL that the user has typed and direct it to its FTP service on the server. So CNAME records are similar to A records but the difference is that A records resolve domain names to IP addresses while CNAMES resolve domain names to domain names. And the next DNS record is MX record or mail exchanger record. And this record is used for email. The MX record simply points to the server where email should be delivered for that domain name. So for example, when you send an email to tom@example.com, your MTA or mail transfer agent will query the MX records for example.com because it's looking for an email server. And then DNS will respond back telling the MTA which server to send the email to which in this case would be mail1.acample.com because that's what the MX record points to. So that's basically what the MX record does. It tells the world which server to send email to for a particular domain name. Now, MX records will generally have two entries, a primary email server and a secondary email server along with priority numbers. The lower the priority number means that it's the primary email server. But if the primary email server gets overwhelmed or goes down, then the secondary email server would be used. And our last record is the TXT or text. Now, this record contains miscellaneous information about a domain such as general or contact information. They are also used to prevent email spam by making sure the incoming email is coming from a trusted and authorized source. So, for example, a TXT record could be a DKIM, which stands for domainkeys identified mail. And this is an email authentication technique that prevents email spoofing. And it does this by adding a cryptographic digital signature to emails. It verifies to receiving email servers that an email truly came from an organization's domain and ensures that it was not tampered with in transit. And another TXT record that's used to prevent email spoofing is SPF, which stands for sender policy framework. And this allows the owner of a domain to publish a list of authorized IP addresses and servers that are allowed to send emails on their behalf. And there's also the demarc TXT record. And this record directs receiving mail servers how to validate the sender of an email and what to do with emails that are not verified by authentication such as SPF or DKIM. It protects an organization's domain against fishing and spoofing. And it's also a requirement for inbox placement on prominent email domains.
Switches connect devices on a LAN, learning MAC addresses to direct traffic efficiently to specific ports.
Now, a switch is a networking device that connects all of your network devices together on a local network. It's a device that has multiple ports that accepts Ethernet connections from network devices. A switch is considered intelligent because a switch can actually learn the physical addresses of the devices that are connected to it and it stores these physical addresses called MAC addresses in its table. So when a data packet is sent to a switch, it's directed only to the intended destination port. So if this computer here wanted to communicate with this computer over here, the data packet arrives at the switch and the switch will look at his table of MAC addresses and matching ports and deliver the data to the correct port and then the data packet would go to that computer.
Managed switches offer advanced configuration options like VLANs and traffic prioritization, while unmanaged switches are plug-and-play.
A switch can be either unmanaged or managed. An unmanaged switch is a basic switch where you would just plug in your devices and that's it. So there is no configuration settings to adjust. These are typically used in small networks. A managed switch is more sophisticated. A managed switch can be configured to do more things such as setting up VLANs, prioritizing traffic, optimizing, and so on. These are typically used in larger enterprise networks.
Routers forward data between different networks based on IP addresses, acting as the gateway for a network.
Now a router does exactly what its name implies. A router is a device that routes or forwards data from one network to another based on their IP address. When a data packet is received from a router, the router inspects the data packet's IP address and determines if the packet was meant for its own network or if it's meant for another network. If the router determines that the data packet is meant for its own network, it'll receive it. But if it's not meant for its own network, it sends it off to another network. So a router is essentially the gateway for a network. So here we have a private network with its router and we'll refer to this as the red network indicated by the red colored screens on the computers. And over here you're going to have different data packets indicated by their different colors which represent different IP addresses. And they are going to be entering the red network's router from the internet. The router is only going to accept the red data packets because they are the only ones intended for this network. So all of the other data packets, the yellows, blues, greens, and so on will be rejected by this router because they were not intended for this network because their IP addresses were not meant for this network.
Firewalls act as security barriers, filtering incoming traffic based on administrator-defined rules to prevent unauthorized access.
A firewall is a system that's designed to prevent unauthorized access from entering a private network by filtering the information that comes in from the internet. It blocks unwanted traffic and permits wanted traffic. So, a firewall's purpose is to create a safety barrier between a private network and the public internet. Because out on the internet, there's always going to be hackers and malicious traffic that may try to penetrate into a private network to cause harm. And a firewall is the main component on a network to prevent this. A firewall that's used on computer networks is similar to how a firewall works in a building structure. In fact, this is where the word firewall came from. A firewall in a building structure provides a barrier so that in the event of an actual fire on either side of the building, the firewall is there to keep the fire contained and keep it from spreading over to the other side. So, it would keep the fire from destroying the whole building. A firewall works by filtering the incoming network data and determines by its rules if it is allowed to enter a network. These rules are also known as an access control list. These rules are customizable and configured by the network administrator. The administrator not only decides what can enter a network but also what can leave a network. So these rules will either allow or deny permission.
Load balancers distribute network traffic evenly across multiple servers to prevent overload and ensure consistent performance.
A load balancer is a piece of hardware or software that is used to evenly distribute data activity across a network so that no single server or computer becomes overwhelmed with the workload. So for example here we have a network and one of the servers is getting more network activity than the other server. So to fix this problem we can add a load balancer so that both servers are sharing the network activity evenly.
NAS (Network Attached Storage) provides centralized data storage accessible over a network, typically for homes and SMBs.
NAS stands for network attached storage. A NAS is a storage device that is used strictly for storing data and it doesn't do anything else besides storing data. Typically, a NAS is a box that may have multiple drives in a RAID configuration for redundancy and a network interface card that directly attaches to a switch or a router so that the data can be accessed over a network. Then once it's on the network, it can be accessed from other devices such as desktops, laptops, and servers as a shared drive. These are typically used in homes and small to medium size businesses.
SAN (Storage Area Network) is a high-speed, dedicated network for massive data storage, known for fault tolerance and recognizing storage as local drives.
And a SAN or storage area network is a special high-speed network that stores and provides access to large amounts of data. Basically, it's a dedicated network that's used for data storage. This network consists of multiple disk arrays, switches, and servers. And because it has multiples of these devices, a SAN is fault tolerant and the data is shared among several disk arrays. So if a switch or a disk array or if a server goes down, the data can still be accessed. And when a server accesses the data, it accesses the data as if it was a local hard drive because that's how operating systems recognize a SAN. It's recognized as a local attached drive rather than a shared network drive like a NAS. And SANs are not cheap. They come at a very high cost, which is why they are mainly used by large companies.
Wireless Access Points (WAPs) extend wired networks, allowing wireless devices to connect and forming a unified network managed by a router.
A wireless access point is basically a wireless hub that's used by wireless devices to connect to an existing wired network. So, it relays data between the wired network and the wireless devices. Now, wireless access points are primarily used by medium to large organizations and typically an organization will have multiple access points to make sure it covers the entire building. So, for example, here we have a medium-sized office and this office has desktop computers, laptops, and tablets. So, the desktop computers will connect to the organization's router using Ethernet cables. But in order for the wireless laptops and tablets to connect to the network, this office is going to use wireless access points. So the access points are going to be placed in strategic places and each of them will connect to the router using an Ethernet cable. Then once that is done, they will all broadcast a Wi-Fi signal so that the laptops and tablets can connect wirelessly and join this network. So now all the desktop computers and wireless devices are joined together in one network and that one network is managed by one single router.
UPS (Uninterruptible Power Supply) provides battery backup during power outages and protects against surges and spikes.
In order to keep a network in constant operation you need to make sure that it always has power. But unfortunately in our world this doesn't always happen. Power outages can happen for several reasons such as storms and blackouts. So, in order to prevent a disruption in network operation from a power loss, you need to use a UPS. UPS stands for uninterrupted power supply. It's a battery backup that supplies power to your equipment if a power outage were to happen. So, for example, this server rack has its own UPS. And if the building were to lose power, the equipment would still be up and running because they are all connected to a UPS and they are now running from battery power. And in addition to supplying backup power, a UPS also protects against surges and spikes.
Patch panels organize network cables in server rooms, reducing clutter and simplifying management.
Now, a patch panel is a flat piece of hardware with network ports that is typically located in a server room or wiring closet, and its purpose is to reduce clutter by keeping your network cables neat and organized. A patch panel is similar to a keystone jack and wall plate. The difference is that a patch panel has a large number of ports and is installed on a server rack near a switch. And a wall plate has a small number of ports and is installed in a wall near a networking device such as a computer. Patch panels also come in different types depending upon what kind of network you're running. There is Ethernet which we just talked about, fiber optic and coaxial.
Power over Ethernet (PoE) delivers both data and DC power over Ethernet cables, eliminating separate power cords for devices.
Power over Ethernet is a technology that delivers DC power to networking devices such as IP phones, security cameras, and wireless access points over the copper wires in an Ethernet cable, which eliminates the need for a separate power cable. So, how does PoE work? How does an Ethernet cable supply a networking device with both data and power? Well, an Ethernet cable has four pairs of twisted pair wires inside. So, it has a total of eight wires. Now, in CAT 5 and previous versions of Ethernet cable, four of those wires are used to transfer data, but the other four wires were not used. So, in a typical networking device, four wires were used for data and four wires weren't used for anything. So in order to supply power to a device, early versions of PoE used the four unused wires to transfer power, while later versions of PoE use all eight wires to transfer power. So here we have a view of a CAT 5 Ethernet cable and its twisted pair wires that haven't been arranged yet. So if we go ahead and straighten out these wires and arrange them to the correct wiring standard, the wires in pins 1 2 3 and six are used for transmitting data. And the wires in pins 4, 5, 7, and 8 are used for transferring power. Now, in order for data and power to be transferred through this cable, it must be connected to a power sourcing equipment or PSE device. A PSE device supplies data and DC power to a power device or PD using an Ethernet cable. So in this example, our PSE device is a PoE switch and our power device on the other end is a PoE IP phone. So when we plug an Ethernet cable into this switch, the switch will send data and power through the cable to the phone. So there's no need for this IP phone to have a separate cable for power because it's getting it through the Ethernet cable.
Active PoE ensures power compatibility before delivery, while passive PoE constantly sends a fixed power level.
There are also two different kinds of power over Ethernet. There is active and passive. When a powered device connects to a PoE switch, power is sent from the switch to that device. But some devices may require different amounts of power than others. So if a device doesn't have enough power, it won't turn on or if it gets too much power, the device could blow up. So this is why active PoE was created. When a power device connects to an active PoE switch, the switch will first test the connection to ensure power compatibility and then it will communicate with that device to be sure it delivers the correct amount of power that the device needs. Now, passive PoE is the dumb version of PoE. It doesn't talk to the devices. It constantly sends power and it sends the same amount of power to whatever device it's connected to. So, this is why it's important to check the voltage requirements of a power device before connecting it to a passive PoE switch because if you connect it to the wrong voltage, it could permanently damage your equipment.
PoE standards have evolved from IEEE 802.3af (Type 1, 15.4W) to 802.3bt (Type 3/4, up to 90W), increasing power delivery capabilities.
Power over Ethernet was first developed by Cisco in the year 2000, which was a mechanism that they created to deliver power and data to their IP phones, similar to how basic landline phones get power using regular telephone lines. And in 2003, the first standardized version of PoE, which was the IEEE 802.3af or better known as type 1, was released. This standard had a power output of 15.4 watts which was enough to power certain devices at that time. So as technology progressed, engineers realized the potential of this technology and created a newer standard to supply power to more power- hungry devices. And in 2009, the IEEE 802.3at standard or type 2 was released, which is also known as PoE plus. And this standard doubled the power output to 30 watts. And in 2011, that power was doubled again to 60 watts when Cisco came out with their own proprietary standard called Cisco universal power over Ethernet. And this led to the release of the IEEE 802.3bt standard or type 3, which is also known as four pair power over Ethernet, which utilized all four pairs of wires. And in 2018, the 802.3bt standard was amended and this had a power output of 90 watts, which is enough to even power a laptop computer.
Modems (cable, DSL, ONT) bring internet into a home/business by connecting to an ISP; DSL uses phone lines, cable uses coaxial, and ONTs use fiber optics.
Now, if you want internet in your home or business, you have to have a modem. A modem is what brings the internet into your home or business. It establishes and maintains a dedicated connection to your internet service provider to give you access to the internet. And one example of a modem is a cable modem. A cable modem is connected to your home using a coaxial cable that provides high-speed broadband internet. And in addition to internet, it can also be used for phone services using voice over IP. Broadband cable is typically provided by the same provider that provides cable television to their customers. And because it's provided by cable television providers, broadband cable leverages the existing infrastructure from cable TV to cover large geographical areas, especially here in the US. And another example is a DSL modem. DSL stands for digital subscriber line. And this is a popular internet technology that is used by homes and businesses to access broadband data over the internet. The DSL modem like this one here uses common telephone lines to carry its data. And it can carry both voice and data at the same time over those telephone lines without using voice over IP like cable does. Now, if you have fiber optic in your home, you would use an, which stands for optical network terminal. And this is a device that's similar to a modem. And its job is to receive light coming from fiber optic cables and convert them into electrical signals that your router uses to deliver internet, TV, and phone services.
A Network Interface Card (NIC) connects a computer to a network, assigning it a unique MAC address for identification.
A network interface card or nick is used to connect a computer to a network. It's basically a circuit board with a network adapter that is installed on your computer or device and its job is to convert incoming serial data into parallel data so that the computer can understand it. A nick provides a constant dedicated connection to a network and every nick has its own unique identifier and this is called a MAC address. The MAC address is an identifier that every network device uses to uniquely identify itself on the network. So no two devices anywhere in the world would have the same MAC address.
WISP provides internet access where traditional providers are unavailable, using towers and antennas.
Now in addition to connecting to the internet using fiber cable or DSL there are also other connection types for internet access and the first one is WISP or wireless internet service provider. Now, WISP is generally provided when fiber, DSL or cable providers are not available, which is common in rural areas. WISP uses towers or base stations on top of high structures to provide a blanket of wireless coverage over certain areas and customers will place antennas such as on the roof of their homes to pick up the wireless signal and access the internet.
Cellular networks use cells and towers for wireless internet access via mobile devices, evolving from 2G/3G to 4G/5G.
Another method of connecting to the internet is by using cellular networks which are used by devices such as cell phones and mobile tablets. Cellular networks divide geographical areas into sections or cells with each cell having a cellular tower to cover that area. It's these cells that allow devices to connect to the internet wirelessly. Early on, cellular networks used technologies such as 2G and 3G. And today, they use modern technologies such as 4G, LTE, and 5G, which significantly increase the speed of cellular data.
Satellite internet offers access in remote areas by relaying data between customer dishes, orbiting satellites, and ground stations.
And there is also satellite internet. Satellite internet is typically used when there is no other option available if you want internet access. and is typically used in undeveloped areas where there is no network infrastructure available. Satellite networks work by data being transmitted by a dish at the customer's location up to orbiting satellites, which the satellites will then relay the data to a broadband internet ground station. And then from there, the ground station will send data back up to the satellites, which will relay the data back to the dish at the customer's location. An example of a satellite internet provider would be Starlink.
Network Types and Tools
LAN (Local Area Network) connects devices in close proximity, like a home or office.
In this section, we're going to be talking about different network types, and these network types depend on how large they are and how much of an area they cover geographically. So, let's first talk about a LAN. Now, LAN stands for local area network. A local area network is a group of devices such as computers, servers, switches, and printers which are located in the same building such as in an office or a home. In other words, in close proximity to each other. And the most common type of LAN is an Ethernet LAN where two or more computers are connected to Ethernet cables using a switch.
WLAN (Wireless Local Area Network) forms a LAN using wireless communication instead of cables.
Now, a WLAN or wireless local area network is a local area network that uses wireless communication instead of wired communication. A WLAN is defined as having at least two devices that use wireless communication to form a local area network. A wireless LAN will typically have a Wi-Fi router or wireless access point for wireless devices such as laptops, tablets, wireless desktops, and smartphones to communicate. So in simple terms, a wireless LAN is a LAN but without using cables.
MAN (Metropolitan Area Network) spans multiple buildings within a city, using high-speed connections like fiber optics.
And the next network type is called a MAN. And MAN stands for metropolitan area network. Now, this is a large network that spans over several buildings in a city or town. Mans are typically connected using a high-speed connection such as a fiber optic cable. It's a high-speed network that gives the ability for sharing data and resources within a city.
WAN (Wide Area Network) covers large geographical areas, with the internet being the prime example.
And then there's the wide area network or WAN. Now, a WAN is the largest type of network. It's a network that spans over a large geographical area such as a country, continent, or even the entire globe. A good example of a wide area network is the internet.
Network tools include cable strippers, wire crimpers, and cable testers for creating and verifying network cables.
In this lesson, we're going to talk about the tools that are used in networking. And if you are already a network technician, then you're already going to be familiar with these tools that I discuss. Now, if you are going to be a network technician, then a lot of times you're going to be creating your own network cables. So, after you have cut the length of the cable you need, the next step is to remove the plastic shielding on the ends of the cable. And this is done by using a cable stripper. So the cable is inserted into the cable stripper and then with a squeeze, twist and a pull, the outer plastic shielding is removed. So after the shielding has been removed, the next step is to arrange the wires in the correct order and then crimp a connector such as an RJ-45 to the cable. And this is done by using a wire crimper. A wire crimper crimps connectors to twisted pair cable. So after you have inserted the wires into the RJ-45 connector, you just place it into the crimper, give it a squeeze, and then the cable is done. The next thing to do is to test the cable. And this is done by using our next tool, which is a cable tester. A cable tester is used to verify continuity and if the wires are arranged correctly. So you would just connect both ends of the cable into the tester and then it will cycle through all the pins in the cable to make sure that the cable is properly wired and connected.
Tone generators (fox and hound) and probes trace cables through complex wiring setups.
A tone generator is also known as a fox and hound. And this is a tool that is used for tracing cables from one end to the other. So, for example, let's say that you wanted to isolate this network cable and find the other end that's connected to this patch panel. And as you can see, this patch panel has multiple cables plugged into it. And this patch panel is located in a different part of the building. So, in this scenario, it'll be very difficult to find the other end of the cable. So, that's where a tone generator comes in. So you just connect the tone generator tool at one end of the cable that you want to isolate and then it will generate a tone through the cable all the way to the other end. And then with the probe, you would just jump from cable to cable on the patch panel until you find the cable. Then once the probe detects the tone coming from the cable, the probe will generate a sound indicating that it has found the cable.
Punchdown tools install wires into punchdown blocks, automatically trimming excess wire.
A punchdown tool is a tool that resembles a screwdriver and this is simply used to connect or punch wires into a punchdown block. A punchdown block is used with telephone equipment where wires are installed. These blocks make it easy to connect wires because you don't have to strip the outer shielding off the cable first. The wires are just inserted using a punchdown tool and then they are punched down into the block. And as the wires are punched down, the punchdown tool will automatically cut off any excess wire.
RJ-45 loopback adapters test network ports by looping transmitted signals back to the input.
Now, there's also an RJ-45 Ethernet loop back adapter. Now, a loop back adapter is a handy little tool that is used to perform a loop back test to see if there are any problems with network ports or connection issues. And it does this by performing a loop back test. Now, to perform a loop back test, the wires in a network cable are arranged in a certain way into an RJ-45 connector where the transmitted signal is looped back into the same connector. So in a loop back adapter's RJ-45 connector, a wire from pin one is connected to pin three and another wire from pin two is connected to pin six. So basically it causes the output signals to be returned or looped back into the input signals to form a complete circuit. Now, you can buy a pre-made loop back adapter tool like this one here, or what a lot of network technicians will do is just make one themselves, like this one here.
Wi-Fi analyzers help troubleshoot wireless networks by assessing signal strength, channels, and nearby access points.
A Wi-Fi analyzer is a tool that helps you understand and improve the operation of your wireless network. It tells you about Wi-Fi signals, such as how strong they are, what channels they are using, and what wireless access points are nearby. You can use this tool for things such as troubleshooting Wi-Fi problems, the best place to put your Wi-Fi access point, and the best channels to use for your network.
Network taps allow administrators to monitor network traffic by intercepting packets between devices.
A network tab enables network administrators to get in the path of network packets. It's a portable network device that gives you access to networks for monitoring purposes and data traffic collection. So, for example, if you wanted to monitor the traffic between a couple of devices, such as a router and a switch, you would connect a network cable from the router and the switch into the network tap and then connect another cable into a device such as a laptop. And now the tap will collect the data packets that are flowing between the switch and the router and then send it to the laptop for an analysis.
Display Technologies and Standards
Displays connect via VGA, DVI, HDMI, DisplayPort, USB-C, or Thunderbolt, outputting visual information from a video card.
Now, a display is the primary output component of a computer. The display connects to the computer's video card using a cable and displays an image on the screen. A display may also have one or several video ports that the cable plugs into. These ports and cables could be VGA, DVI, HDMI, or Displayport. And some modern displays may include USB-C and Thunderbolt ports.
LCD (Liquid Crystal Display) technology uses backlighting and liquid crystals to produce images on a flat panel.
Now, one type of display is called an LCD. LCD stands for liquid crystal display. These are lighter, thinner, use less power, and take up less space than the older CRTs. LCDs are also known as flat panel displays. LCDs produce an image on a flat surface by using liquid crystals. A backlight shines through these crystals to produce an image on the screen and it uses filters to produce the different colors. LCDs were first used in laptop computers and now it's the primary type of monitor that's used for desktops.
LED displays are LCDs with LED backlighting, offering better color accuracy and contrast than older fluorescent backlights.
Also, in order for LCD monitors to show an image on the screen, it needs to have a light source. And there are a couple of different types of backlighting that an LCD display uses. The older type of lighting is by using fluorescent lamps. These fluorescent lamps are circular glass straight tubing types similar to regular fluorescent lamps that we're all used to seeing. These lamps emit ultraviolet light that's created when the mercury vapor inside the lamp is ionized. And another type of backlighting that LCD monitors use is LED. LED displays use multiple light emitting diodes that are arranged in a pattern that displays the images on the screen. Now, this is a modern type of backlighting compared to the older fluorescent lamp backlighting. The advantages that LED monitors have over standard LCD is that it can produce sharper and more accurate colors. Now, both of these displays are considered LCD. However, the LCD that uses the LED backlighting is considered an LED display. So, an LED display is just an LCD display that uses LED backlighting. And most if not all new LCDs use LED backlighting.
LCD panels (TN, VA, IPS) vary in performance, color reproduction, and viewing angles; TN is fastest for gaming, IPS has best colors/angles, VA is a balance.
Now LCDs will have three different types of flat panels. These types are TN, VA and IPS. And these will vary in performance, color reproduction, and price. So the first one is TN. And TN stands for twisted pneumatic. This type of LCD works by liquid crystals actually twisting the light as it comes through. TN is the oldest of the three, which makes it the most affordable, but it's also the best as far as performance because it will have the highest refresh rates and the fastest response time, which makes it ideal for gaming. When a monitor has a fast response time, it helps eliminate ghosting. Ghosting is when an image on a monitor leaves a trail behind as it moves across the screen. And since TN monitors are the fastest, they are the best at eliminating ghosting when compared to other displays. However, TN displays do have some drawbacks. And one of those drawbacks is color reproduction, which are not good as the other types. And another drawback is poor viewing angles, especially on the vertical axis. Now a newer and more modern type of flat panel is IPS. IPS stands for inplane switching. IPS was developed because of the limitations of TN monitors. This type of display works by instead of the liquid crystals twisting like in a TN monitor, the liquid crystals in an IPS will stay in place and are aligned in parallel with the glass. And because of this, an IPS monitor will have better and more accurate color reproduction, and it'll also have a better viewing angle than a TN display. So, if you were to view a TN and an IPS monitor on a vertical angle, the IPS will look relatively the same, but on a TN, the image will dramatically change. So, as you can see, the colors get washed out. But the disadvantage of an IPS is that they are more expensive. They will also have a lower refresh rate and they will also have a slower response time than TN displays. Now, a VA or vertical alignment display is in the middle. VA displays will have a refresh rate and response time faster than an IPS, but slower than a TN. and it will have a better color reproduction than a TN, but not as good as an IPS. So, it's basically a mixture of a TN and an IPS.
OLED displays use self-emissive pixels for perfect blacks, high contrast, and vibrant colors, surpassing LED backlighting.
And another type of display is an OLED, which stands for organic light emitting diode. OLED is used on modern smartphones and high-end TVs. The biggest difference between OLED and the standard LCD and LED displays is the light source. So, as I stated before, LCD monitors will use fluorescent bulbs or LEDs for backlighting, but OLED displays are different. With OLED, each pixel will produce its own illumination without having a separate backlight. Electrical current is applied to organic compounds that cause them to glow. OLED displays are relatively new in the marketplace, so they are more expensive. They produce great colors, including producing the darkest black color available today with the highest contrast ratio. A standard LED will have a contrast ratio of 1,000 to 1, but an OLED will have a contrast ratio of 100,000 to 1.
Mini LED technology, an advancement in LCD, uses microscopic LEDs for deeper blacks, brighter highlights, and greater contrast.
And there's also the mini LED. And the mini LED is the next generation of LCD display technology. Mini LED doesn't use traditional backlighting like a standard LED does. Instead, it uses thousands of microscopic LEDs. This results in deeper black levels, brighter highlights, and a greater contrast.
Touchscreens utilize digitizers to detect finger touches, replacing mouse clicks for input on various devices.
A touchscreen is a display with an input detection system or digitizer. It's a transparent grid that senses a touch by a finger. It works the same way as if you were using a mouse but without the mouse itself because you are using your finger instead. The touchscreen receives a touch in the same way as if you were clicking a mouse button. Typically, one click on the mouse button equals one tap by a finger and two clicks of the mouse equals two taps by your finger. Touchscreens are commonly used in all-in-one computers, tablets, and smartphones.
Resolution (pixels) determines image clarity; higher resolution means more pixels and a sharper image.
And another thing to know about displays is the resolution. Resolution is defined by the number of pixels that are used to display an image on the screen. A pixel is the smallest element in an image. The higher the resolution, the higher number of pixels will be used, which means a clearer and sharper image. And displays may come in different max resolutions. So, as an example, if a display has a max resolution of 1280 by 720, which is called HD or high definition, this means that there are 1280 horizontal pixels by 720 vertical pixels, which means that there are over 900,000 pixels that are being used.
Pixel density (PPI) indicates pixel spacing for image detail; higher PPI means fewer visible pixels and clearer images.
Now the amount of closely spaced pixels on a display is measured by pixel density. Pixel density is expressed as PPI or pixels per inch. A higher PPI results in fewer noticeable individual pixels and clearer, more detailed images.
Refresh rate (Hz) indicates how often an image is updated, reducing eye strain and motion blur for smoother visuals.
And there is also the term refresh rate. The refresh rate refers to the number of times that an image on the display is updated. The refresh rate is measured in hertz. So for example, if the refresh rate is 60 Hz, then that means that the image updates the entire face of the display at a rate of 60 times per second. And today, some higher-end LCD monitors may have refresh rates as high as 240 Hz. Having a higher refresh rate reduces eye discomfort. It'll reduce motion blur and will give you a smoother visual experience.
Response time (ms) is the duration for a pixel to change color, with faster times minimizing ghosting.
The response time is the time in milliseconds that it takes for a display to change from one color to another color. For example, from black to white. A very fast response time would be 1 millisecond as compared to a slower response time of 10 milliseconds.
Color gamut defines the range of colors a device can capture or generate.
Color gamut refers to the range of colors that a given device can capture or generate. On the chromaticity diagram, it's normally displayed as a closed area of the primary colors of a device. So for example, on a display, the primary colors are red, green, and blue. Therefore, the color gamut of a display is a triangle with the red, green, and blue colors surrounding it.
Cabling and Connectors
Twisted pair cables (UTP, STP) use pairs of wires to transmit data, with twists minimizing electromagnetic interference.
The most common network cable that is used today are twisted pair cables. These are the cables that you'll find as you connect a computer to a switch so we can join a network. Now, Ethernet twisted pair cables come in two different types. And the first type is unshielded twisted pair, which is by far the most common type of cable that is used today. Unshielded twisted pair consists of four pairs of color-coded wires twisted around each other. The wires are twisted to prevent electromagnetic interference or cross talk. This type of cable is what most people would use in their home or business. And the second type is shielded twisted pair. Now shielded twisted pair is very similar to unshielded twisted pair except that it has a foil shield that covers the wires. And this shielding is what adds an extra layer of protection against electromagnetic interference leaking into and out of the cable. This type of cable is mainly used for industrial purposes and not so much in a home or business. And there are also direct burial STP cables. Now these are heavy duty networking cables that are designed to be buried underground. They will have a rugged waterproof outer jacket with a gel-filled core for better protection from outside exposure.
Cable wiring standards (568A and 568B) dictate the order of wires for straight-through and crossover cables.
Now, before you attach an RJ-45 connector, the wires in a cable need to be arranged in a certain order, and that order will be different depending upon the purpose of the cable. So, for example, the most common types of twisted pair cables that are used in local area networks are straight and crossover cables. And there are two wiring order standards that are used. One standard is 568A and the other is 568B. And on the screen you can see the wiring order for both A and B standards. The order is based on the color of the wires. So for example the 568 wiring standard is wired in this order. white, green, green, white, orange, blue, white, blue, orange, white, brown, and brown. And the 568B standard is wired in the following order. White, orange, orange, white, green, blue, white, blue, green, white, brown, and brown. The only difference between the A and B standards is the green wires are swapped with the orange and it doesn't matter which standard you use. But here in the US, most people use the B standard.
Twisted pair cable categories (CAT 3 to CAT 8) define maximum speeds without crosstalk, with higher categories supporting faster data rates.
Now, in addition to talking about the different types of twisted pair cables, we also have to talk about the categories of twisted pair cables. And these categories are called CAT 3, CAT 5, CAT 6, CAT 7 and CAT 8. And the difference between these cables is the maximum speed that they can handle without having any cross talk or interference. The numbers of these categories represent the tightness of the twists that are applied to the wires. And you can see on the illustration of the categories and speeds of the different twisted pair cables. So you can see the speed ranges from the lowest category which is CAT 3 at 10 megabits per second and all the way up to CAT 6a and CAT 7 which has speeds of 10 gigabits per second. Now most networks today would use at least CAT 5e because most networks would be running at least at gigabit speeds. So CAT 3 and CAT 5 are slower than gigabit and are pretty much obsolete today. But of course, if you're running a network that can handle 10 gigabit speeds, then you would have to use CAT 6a or CAT 7 on your network. And finally, there's the latest version, which is CAT 8. Now, CAT 8 is the ultimate copper cable. It's a shielded twisted pair cable that has a delivery speed of 40 gigabits per second up to a distance of 30 meters.
Plenum cables, fire-resistant and low-toxicity, are required for cables running through open air spaces in buildings to prevent fire spread.
Now, the term plenum refers to a space in a building where there is open air flow. circulation. This is usually between the drop ceiling and the structural ceiling. So, as a result, buildings that have plenum spaces where there is adequate open air flow are more prone to fires than buildings that don't have plenum spaces. So, therefore, cables that run through plenum spaces must meet certain requirements. First, the cable must be more fire resistant and secondly, they must not produce any toxic fumes if they are burned. So in this environment, this is where plenum cables should be used. Now buildings that don't have plenum spaces will have air ducts encapsulating the airflow. So there is no open airflow circulation because of these air ducts. So the chances of a fire happening and recirculating toxic fumes are minimal. So this is where you could use non plenum cables.
Coaxial cables, used for broadband internet and cable TV, come in RG-6 (long distance) and RG-59 (short distance video) types.
This is the coaxial cable. This is used today primarily by cable providers to provide a computer with broadband internet connection. Early on, it was used as a backbone for networks such as a bus network. There are two common types of coaxial cable. The first type is RG-6 and this is made for long distances and is commonly used for cable television and internet connection. And the second type is RG-59. This is made for short distances and is commonly used for high definition and high quality video.
Fiber optic cables use light pulses for high-speed data transmission over long distances.
So now we're getting into fiber optic cables. So here is a cutaway view of a fiber optic cable and a light source. Fiber optic cable uses pulses of light to send data and as a result it is very fast and it can span for great distances.
Single-mode fiber is for long distances, while multi-mode fiber is for shorter distances, with light reflecting internally.
Now there are two different modes in fiber optics. Single mode fiber and multimode fiber. Single mode fiber is a fiber optic cable that allows light to enter only at a single angle as you can see here. So when this type of transmission of light enters at this angle, it can span for great distances. And this is multimode fiber. The difference between multi mode and single mode is that in multimode, light travels in multiple beams that reflect off the walls of the cable. And unlike single mode fiber, multimode fiber is made for short distances.
RJ-11 connectors are four-wire connectors mainly for telephone equipment, but also used for modems in networking.
And this is the RJ-11 connector. This is a four-wire connector that's mainly used to connect telephone equipment. But as far as networking, the RJ-11 is used to connect computers to a local area network through the computer's modem. The RJ-11 locks itself into place by a single locking tab, and it resembles the RJ-45, but it's a little bit smaller.
RJ-45 connectors are standard 8-pin connectors for Ethernet twisted pair cables, used to connect devices to networks.
Now, the RJ-45 is by far the most common network connector. Now, this is an 8-pin connector that's used to connect computers and other network devices in a local area network. The RJ-45 is used with unshielded twisted pair cable. Twisted pair cable has eight wires and these wires are arranged in a certain order and then the wires are inserted into an RJ-45 connector and then they are crimped on both ends using a wire crimper and then one connector will be plugged into the computer's network card and then the other end would plug into a device such as a switch modem or a router. Then once that is done, the computer will be able to connect to a network. The RJ-45 has a single locking tab that locks itself into place.
F-type connectors are threaded connectors for coaxial cables, commonly used with cable modems and satellite internet.
Now, this connector is called the F-type. Now, this is a threaded connector typically used on coaxial cables. These are primarily used by cable providers to attach to cable modems. So, if you have broadband cable like I do, you will have a modem with a coaxial cable attached to an F-type connector that screws into the back of your modem that attaches with a nut. And in addition to being used with broadband cable, they are also used with satellite internet.
Fiber optic connectors (SC, LC, ST) facilitate secure connections for fiber optic cables.
So, now we're getting into fiber optic connectors. So the first fiber optic connector is called the SC or standard connector and this is often called the square connector and this was one of the first connectors to be used in the marketplace. This uses a push-pull connector similar to audio and video plugs and these are commonly used between floors in a building. And our next fiber connector is called the LC or local connector or Lucent connector since it was developed by Lucent. Now, this type of connector is also commonly used between floors in a building and it was designed to compete with the SC connector. It's about half the size of the SC connector, which makes it better for highly populated racks and panels. And this also uses a latch that locks itself into place similar to the RJ-45. And our last fiber optic connector is called the ST or straight tip. Now this uses a half twist bayonet type of lock and is commonly used with single mode fiber optic cable. Now, this is a large size connector that was developed by AT&T. And because of its large size, its usage has declined in favor of smaller connectors such as the LC and the MTRJ.
Punchdown blocks terminate wires, using special tools to connect them into the block's metal contacts.
A punchdown block is a terminal block where wires are inserted. To create an electrical connection, you would punch down the electrical wires into slotted metal contacts that cut the insulation using a punchdown tool.
VGA (Video Graphics Array) is an older analog video port, gradually being replaced by digital interfaces.
VGA stands for video graphics array. Now, this is an older video port that's been around for a while. In fact, it's been around since 1987. The VGA port has 15 pins divided into three rows, and it only carries analog data. And because it only carries analog data, the quality of the video may degrade at higher resolutions and longer cable lengths. And the end adapter would typically have a blue color. The VGA port was first used on now extinct bulky CRT monitors, but you can still find them on some new equipment such as new LCD monitors. But as I stated before, the VGA is an old design and is slowly being phased out in favor of more modern designs.
DVI (Digital Visual Interface) offers analog, digital, or integrated signal transmission for uncompressed video.
DVI stands for a digital visual interface and this has succeeded the VGA port. It was first developed in 1999 and it was designed to provide uncompressed high quality video to LCD monitors. Now there are three different versions of DVI. There's DVI-A where the A stands for analog and this is used to send only analog signals. There's also the DVI-D where the D stands for digital and this is used to send only digital signals. There is also the DVI-I where the I stands for integrated and this is used to send both analog and digital signals.
HDMI (High-Definition Multimedia Interface) transmits uncompressed digital video and audio over a single cable, supporting Ethernet data.
And this is the HDMI port. HDMI stands for a high definition multimedia interface. HDMI has a broad range of use in electronic products such as TVs, monitors, laptops, mobile devices, and so on. It was developed back in 2002, and it was designed to transmit uncompressed video and audio digital data through a single cable. HDMI is one of the best standards for high definition in consumer electronics, delivering crystal clear video as well as audio. And in 2009, HDMI 1.4 was released. And this added another channel to HDMI for data, which has the capacity of network communication. So, the connected devices that use this feature will give HDMI the ability to send and receive Ethernet data.
DisplayPort, designed for video, also carries USB and audio, excels at multi-monitor setups via daisy-chaining, and features a locking mechanism.
And then there's also the DisplayPort. The DisplayPort was developed in 2006 and it was developed by VESA which stands for the video electronic standards association. The display port was primarily designed to be used for video. But in addition to video, it can also be used to carry USB and audio data as well. It's a high performance interface that is meant to replace the older VGA and DVI interfaces. One of the main advantages it has over HDMI is that it has multimonitor capabilities. The DisplayPort allows you to use multiple monitors by connecting them in a daisy chain configuration. So, for example, if you wanted to use three monitors on your computer, you would connect a cable from the display port on your computer and then the other end to the first monitor. And then the first monitor you would connect directly to the second monitor and then from the second monitor you would connect to a third monitor. So now you'll have three working monitors while using only one DisplayPort on your computer. And this is why the DisplayPort is more focused for computer use than for other equipment such as TVs. Another advantage is that the DisplayPort has a locking mechanism that keeps the cable locked in place.
Thunderbolt is a high-speed interface combining PCI Express and DisplayPort, supporting multiple peripherals and daisy-chaining up to six devices.
Thunderbolt is a high-speed technology interface that outputs one serial signal from a combination of PCI Express and the DisplayPort. Thunderbolt is not just for connecting video, but it's also used for attaching other external peripherals as well. In fact, it can be used to daisy chain up to six devices. Thunderbolt was released in 2011 and was mainly used in Apple products and now it has become available to PCs. Now, there are five different versions of Thunderbolt. Versions one and two use the same connector as the mini DisplayPort. And versions three, four, and five use a USB type C connector.
USB (Universal Serial Bus) is the standard for connecting peripherals, evolving from 1.0 to 3.0+ with significantly increased speeds.
Peripherals are devices such as printers that are connected to your computer using a peripheral cable. These cables allow communication between your computer and the device. And in certain circumstances, it can also supply power at the same time. It's also used to charge devices such as cell phones. And the most common peripheral cable is the USB cable. USB stands for universal serial bus. The USB is the standard that is used to connect peripherals to a computer and it's the most commonly used port. The first USB version was released in 1996 starting with USB 1.0 with later versions released throughout the years. USB 1.0 had a transfer speed of 1.5 megabits per second and 2 years later in 1998 USB 1.1 was released and this had a transfer speed of 12 megabits per second. Then in the year 2000 USB 2.0 which is also known as high-speed USB was released and this had a significant speed upgrade from USB 1.1 with speeds of 480 megabits per second. And in 2008, USB 3.0 was released and this was known as super speed USB. USB 3.0 boasts speeds of 5 gigabits per second, which is approximately 10 times faster than USB 2.0. This high speed was meant for transferring large amounts of data, such as backing up to external hard drives. USB 3.0 ports and cables will also have a blue color compared to black or white on previous USB versions and it's also backwards compatible with USB 2.0.
Molex connectors are older 4-pin power connectors for drives and fans, largely replaced by SATA.
There is also the Molex connector. The Molex connector is a 4-pin socket connector. Now, this is an older connector that's used to supply power to older hard drives and optical drives. These have largely been replaced by the SATA connector, but today these can also be used to power cooling fans. These connectors were oftentimes a pain to work with because it was a hassle to get the pins lined up when plugging them in.
Serial cables (e.g., RS-232) transmit data one bit at a time, used for industrial equipment and older devices.
There are also serial cables that can be used to connect devices to a computer. And serial cables, the data travels in a serial path, meaning one bit at a time. These cables are mostly used for network devices, industrial equipment, and older computers. A common interface of a serial port is the RS-232 standard which uses the common D connector such as the DB-9 and DB-25.
Computer Memory and Storage
RAM (Random Access Memory) is temporary storage for data and programs, allowing fast CPU access.
In this section we're going to be talking about primary or temporary storage and this is called RAM. RAM stands for random access memory. In order for data or a program to run, it needs to be loaded into RAM first. So, here is how it works. The data or program is stored on a storage drive such as a hard drive or SSD and then from the storage drive, it is loaded into RAM. And then once it's loaded into RAM, the CPU can now access that data and run the program. Now a lot of times if the memory is too low it might not be able to hold all the data that the CPU needs and when this happens then some of the data needs to be kept on the storage drive to compensate for the low memory. So instead of data going from the RAM to the CPU it has to do extra work by going back to the storage drive. And when this happens it slows down the computer. So to solve this problem, all you need to do is increase the amount of RAM on the computer. And by doing this, all the data can be loaded into RAM without the need of constantly accessing the storage drive. And the result is a faster performing computer.
RAM requires constant power; data is lost when power is removed. It's stored on DIMM modules.
RAM requires constant electrical power to store data. And if the power is turned off, then all the data is erased. RAM is stored on the motherboard in modules that are called DIMMs or dual inline memory modules. And these DIMMs come in different memory sizes. Today, they can range anywhere from 2 GB up to 128 GB per DIMM.
DRAM needs frequent refreshing due to capacitors; SDRAM synchronizes with the system clock for faster performance.
RAM also comes in different types such as dynamic RAM or DRAM. DRAM is memory that contains capacitors and because it contains capacitors, it has to be refreshed often. And another type of memory is called SDRAM which stands for synchronous DRAM. This type of memory is what is used today on RAM DIMMs. The difference between SDRAM and DRAM is basically speed. The older DRAM technology operates asynchronously with the system clock which basically means that it runs slower than the system clock because its signals are not coordinated with it. But SDRAM runs in sync with the system clock which is why it is faster than DRAM. All the signals are tied to the system clock for a better controlled timing.
SODIMMs are smaller RAM modules used in laptops and other compact devices.
And there is also SODIMMs or small outline dualinline memory modules. Now these are used in smaller devices such as laptops. SODIMMs are roughly half the size of regular DIMMs.
ECC (Error Correcting Code) RAM detects and corrects memory errors, primarily used in servers for reliability.
Some RAM modules have ECC, which stands for error correcting code. And what this does is that it detects if the data was correctly processed by the memory module and makes a correction if it needs to. You can tell if a RAM module has ECC by counting the number of memory chips on the module. In a standard NON ECC, it'll have eight memory chips, but in an ECC module, it'll have nine memory chips. Most RAM modules today are NON ECC and this is because of the advance in technology that has minimized memory errors and has made NON ECC RAM more stable. Typically today, ECC memory is mostly used in servers because servers need to be up and running at all times and using ECC memory is just an extra precaution to guard against any memory errors.
DDR (Double Data Rate) RAM uses both rising and falling clock edges for increased data transfer speeds compared to non-DDR.
As technology increased and processor and bus speeds got faster, a new RAM technology was developed to keep up with the faster speeds of computers. This newer technology was called DDR, which stands for double data rate. And that's basically what DDR does. It sends double the amount of data in each clock signal when compared to non DDR RAM. Non DDR or single data rate RAM uses only the rising edge of the signal to transfer data. But DDR uses both the rising and falling edges of the clock signal to send data, which makes DDR twice as fast. DDR has come out with different standards over the years, starting with DDR1 in 1998, and then all the way up to the latest standard, which is DDR5, which came out in 2020.
Multichannel memory (e.g., dual channel) further enhances performance by allowing simultaneous data access from multiple memory modules.
To meet the higher demands of faster processors and memory controllers, another new technology was developed called multi-channel memory. So, for example, there's dual channel memory.
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