Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- So what is a computer network? Well, first, what is a network? The definition of a network is "A group or system of interconnected people or things" So, it would be fair to say, a computer network would be “A group or system of interconnected computers” right? And that’s exactly what it is. A computer network is anything where more than one computer is connected. Traditionally, a computer network would consist of desktop computers, servers, printers, etc. These days, we live in a connected world. We still have desktops, servers, and printers, but now we have a vast number of smart devices connected to our networks as well. Most of you will have a mobile phone, maybe a tablet. Security cameras and even smart lighting systems can be found on networks! And the list goes on and on! Networking has changed the world and how we live in it. It’s a topic I still get excited about and there is no shortage of new things to learn. We will go over a lot of this in more details as we go but that enough for now #ccna #cisco #networking

Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- This video will go over basic network devices. We will see how they work and what they are used for. Hubs Hubs were around before switches. A Hubs job is to forward traffic from the source device to the destination device. A hub is a layer 1 (physical layer) device which means that is does not understand MAC or IP addresses. This is a problem. Because the hub does not know where the destination device is located, it will send traffic out of all ports (except the receiving port) causing collisions and queues which results in packet loss and delays. Due to the horrific down falls, hubs have been replaced with switches almost everywhere. Bridges Bridges are used to separate a LAN network in to segments so that traffic is not sent between them. They work by using layer 2 (data link later) to identify the where traffic should be sent. Now it is worth noting that bridges will send traffic out all ports until it learns (using MAC address) where each port leads. Switches You could think of a switch as the heart of a network, pumping blood (traffic) around the body (network). All Devices will connect to the switch and it is the switches job to send the traffic to the correct place. Now unlike a hub, a switch can learn the mac addresses of each port using a Mac Address Table and can also send and receive at the same tine which means no more collisions or delays. Routers We have all heard of them and most likely everyone you know will have one in their home. If your reading this on a computer then I bet there is one right next to you. A router connects your LAN to other networks such as the internet. If your house was a LAN network, your door would be the router. It is the way ‘outside’ of your network. #ccna #cisco #networking

Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- The OSI Model Explained What Is this OSI Model? The OSI model (Open System Interconnect) is a theoretical stack of 7 layers that can be used as a reference to understand how a network operates. The model was introduced to standardize networks in a way that allowed multi-vendor systems, prior to this you would only be able to have a one vendor network as the devices could not communicate with other vendor devices. The Layers Application (layer 7) This layer is where the application and user communicates. Application specific protocols are used here such as SMTP (simple mail transfer protocol) for sending emails from Outlook. Presentation (layer 6) This layer formats the data in a way that the receiving application can understand it. This layer is also able to encrypt and decrypt date if needed. Session (layer 5) This layer is responsible for establishing and terminating of connections between devices. Transport (layer 4) The transport layer of OSI Model is used for error handling and sequencing to unsure no data is lost. This layer also adds source and destination port numbers Network (layer 3) The network layer handles IP address routing. At this stage of the OSI model the source and destination IP address is added to the data. Data Link (layer 2) At this layer the physical address (MAC Address) is added to the data, this includes the source and destination MAC address. Physical (layer 1) The physical layer is the lowest layer of the OSI model. Its key responsibility is to carry the data across the physical hardware such as an Ethernet cable to the destination. This video is designed to give a basic and general overview of the OSI model. Its aim is to simplify the concept to make it easier to understand. #ccna #cisco #networking

Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- What is the TCP/IP model? It's a model to standardise computer networking. The OSI model, while widely referenced isn't used in the real world. The TCP/IP model, however, is the real deal. Thankfully, it's not all that different. Here is the original TCP/IP model. Application, Transport, Internet, and Link. Just like the OSI model, it's numbered from the bottom up but the direction depends if you're sending or receiving traffic. So this is the original TCP/IP model, but, it has been updated. The link-layer has been split into Data Link and Physical and the Internet Layer has been renamed the Network layer. Layer 5: Application protocols such as HTTP, FTP, and SMTP Layer 4: The two most common transport protocols are TCP and UDP. Port numbers are also added here. Layer 3: At the Network layer, we have the Internet Protocol or IP. Routers also commonly operate at this layer Layer 2: The data link layer contains Ethernet related protocols. Switches usually operate at this layer. Although you can get layer 3 switches that have routing capabilities Layer 1: Think of everything you can touch and feel here. Things like cables, hubs and Network interface cards. #ccna #cisco #networking

Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- The two primary protocols at the transport layer are TCP and UDP. A network application has to choose how to send its data. That choice comes down to reliable or unreliable transmission. Both reliable and unreliable have their benefits and drawbacks. TCP (Transmission control protocol) is the most widely chosen option for transmitting data. This is because it can reliably send and receive data. The way TCP can provide such stable and reliable connections is in three ways. 1. Acknowledgements 2. Sequencing 3. Checksum But, before any of that can happen, first we need to start a reliable connection. TCP does this by using what's called a three-way handshake. 1. SYN 2. SYN-ACK 3. ACK Now we have an open TCP connection. A similar process will be followed when closing this connection as well. UDP (User Datagram Protocol) has none of the error handling, sequencing or reliability of TCP. You can think of UDP as a kind of machine gun of data. Just firing and firing not caring if data is lost or not. While TCP offers great connection and reliability, it comes at a price or resource and latency. Where UDP is very useful is in a situation when we need live, real-time connections. For example, voice calls, video calls, and gaming all need fast real-time connections. That’s it for the TCP and UDP, two ways to send data, for two different purposes. If you liked this video, don't forget to like, comment and subscribe. #ccna #cisco #networking

Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- In the last video, we looked at the layer 4 protocols TCP and UDP. Layer 4 is also responsible for choosing port numbers. So why do we need port numbers? The example I give here is the postal service. To get post, you install a letterbox (at least here in the UK). This letterbox allows the postal service to access your home. Network applications work in the same way. If you want to communicate over a network, you must allow some means of access to your device. Let's say we want to access a web server. We type in the web address (also known as a URL) of the site we want to visit. The first thing the computer does it convert that URL to an IP address. This is done by using DNS, but we will cover than in another video. For now, just know it coverts web addresses to IP addresses. The computer then sends the request to the webserver. The server will then look at the destination port to find out which application to send this data to. It can do this because there is a standard that port numbers follow. When we made our web request, our computer knew we were trying to access a HTTP site. So it added the destination port number 80 to the TCP header. The computer will also choose a randomly generated source port to receive reply’s on. Several port numbers are called well-known ports. These are common protocols that have been assigned port numbers. Examples of well-known port numbers are HTTP(80), HTTPS(443), SMTP (25). 0 – 1023: Well-known port numbers. 1024 – 49151: Registered ports that companies have registered IANA 49152-65535: Dynamic ports Resources: https://tools.ietf.org/html/rfc6335 https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml #ccna #cisco #networking

Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- What is an IP address? An IP address is A unique identifier assigned to each device connected to a computer network The most common analogy for an IP address is the postal service. For the postal service to work, every house needs to have its own, unique address. If you need to send a letter, you'll need to write the destination address on the envelope. That way, when you send your letter, the postman knows exactly where to deliver it. Computers work in the same way. Each computer in a network needs to have a unique address, called an IP address. and when sending data to a computer, just like letters, we need to add the destination address. We also need to include a return address, so they know where to reply. An IPv4 address is 32-bits in length. It contains 4 sections, which are called octets. These octets are separated by periods. Each octet can, in theory, contain any number between 0 - 255 The IP address is separated into two parts. The first part represents the network and the second part represents the host. To know which part of an IP address represents the network, we use something called a subnet mask. In its simplest form, wherever you see 255. this is the network part of the address and wherever you see a zero, this is the host part of the address, IP Address Classes It was decided to split all of the available addresses into groups called classes. The idea was to make address allocation scalable. We have class A, class B, and class C. Class D and E are reserved. Class A addresses are between 1.0.0.0 to 126.255.255.255 0.0.0.0 and 127.0.0.0 are class A addresses but are reserved With a subnet mask of 255.0.0.0 Max Hosts: 16,777,214 Class B addresses are between 128.0.0.0 to 191.255.255.255 With a subnet mask of 255.255.0.0 Max Hosts: 65,534 and class C addresses are between 192.0.0.0 - 223.255.255.255 With a subnet mask of 255.255.255.0 Max Hosts:254 Private IP Addresses But there’s a problem. The problem is that no one could have predicted the massive explosion of computers and the internet. In fact, there are no more unallocated Ipv4 addresses left. That is why the new Ipv6 has been designed to give us more than enough IP addresses for everyone. To help prolong the life of IPv4, we have carved out a small section from all three classes and called them, private IP addresses. Private class A addresses are between 10.0.0.0 - 10.255.255.255 Private class B addresses are between 172.16.0.0 - 172.32.255.255 Private class C addresses are between 192.168.0.0 - 192.168.255.255 #ccna #cisco #networking

Join the Discord Server! https://discord.com/invite/QZ2B9GA3BH --------------------- MY FULL CCNA COURSE 📹 CCNA - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA FREE CCNA FLASHCARDS 🃏 CCNA Flashcards - https://certbros.com/ccna/flashcards HOW TO PASS THE CCNA 📚 Get a great book - https://amzn.to/3f16QA5 📹 Take a video course - https://certbros.teachable.com/p/cisco-ccna?utm_source=youtube&utm_medium=desc&utm_campaign=CCNA ✔ Use practice exams - https://www.certbros.com/ccna/Exsim SOCIAL 🐦 Twitter - https://twitter.com/certbros 📸 Instagram - https://www.instagram.com/certbros 👔 LinkedIn - https://www.linkedin.com/company/certbros 💬 Discord - https://www.certbros.com/discord Disclaimer: These are affiliate links. If you purchase using these links, I'll receive a small commission at no extra charge to you. --------------------------------------------------------------------------------------------------------------- When we type in an IP address, the computer will convert that into binary. And to fully understand how IP addresses work, we need to be able to do the same. An IPv4 address is 32 bits long. This means the address is made up of 32 binary digits. Each digit is called a bit. The IP address contains 4 octets. Each octet contains 8 binary bits. Each bit can either be a 1 or a 0. A bit represents a value of 1, 2, 4, 8, 16, 32, 64 or 128. That value doubles in size from right to left. This is called the power of 2. We also need to think about subnet masks. Previously I said, wherever there is 255, this is the network section and wherever there is a 0, this is the host section. That’s true in the simplest form, however, it can get a bit more complicated than that. The real way to see which part of an IP address is the network section is by looking at the subnet mask binary bits and comparing it to the IP address binary bits. Anytime you see a 1 value, this bit is the network section and anytime you see a 0 it’s the host section. Instead of the full subnet mask, you will often see it written as a forward slash, and then the number of network binary bits. For example, instead of 255.255.255.0, we could write it as /24. This is usually added to the end of the IP address. #ccna #cisco #networking