Free CCNA Course | Network Devices | Lecture 1 | CCNA 200-301 Course

Welcome to this complete CCNA Cisco Certified Network Associate course.

This is a complete course for the CCNA, including everything you need to know in order to pass your CCNA exam.

There will be a tutorial article for every topic in the exam topic list, which will explain in detail everything you need to know about the topic, like the terminologies and some of the commands that you will need for each topic.

At the end of each lecture, there will be a practice quiz to test your understanding of the topic. This quiz is there to help you memorize most of the important concepts and commands covered in each topic.

After each lecture, there will be a practice lab where we will give a pre-created network topology with a configuration objective and you are required to give it a try. A solution to each practice lab will also be treated. This practice lab is to give you hands-on practice configuring and troubleshooting network devices.


The only requirement for this course is basic familiarity with computers. You don’t need any prior knowledge to follow up on everything we will be covering in this course.

Let’s get started.

What Is a Network?

A computer network is a digital communication system that allows network nodes to share resources. This resource could be data, a file, or a voice traffic.

A network node is a device that helps share or receive information in a network. Examples of network nodes are routers, switches, servers, firewalls, or laptops. Two or more of this network nodes joined together is called a network. For example, the image below showing a PC Joined to a server using a cable is a Network because they can share resources together.

a simple network comprising of a server and pc

Network Devices

For a good start of this course, it is very important we get you familiar with some of network devices that we will inevitably be making use of in the rest of this course.


A server is a device that provides services to a client. A server hosts files like images, programs, webpages, data, etc. and shares them with a client on request. In networking, the symbol of a server is shown below:

symbol of a server

Although we traditionally have computer devices that are dedicated servers, every end device can act as a server.

When two devices are communicating in a network, one of the devices asks the other to share a resource it does not have. For instance, if PC1 and PC2 are connected to a network, PC1 may ask PC2 to send it an image file that it does not have. In this case, PC2 is a server and PC1 is a client.


A client is a network device that receives a service from a computer server. In a network, a client will request a resource that it does not have from another computer. If the computer renders the services, it is termed a server, and the PC that received the resources is a client.

In a computer network, a client could be a laptop, a smartphone, a printer, or other end devices.

network clients

Remember: A network device can act as a server in one situation and as a client in another situation.

3. Switches

Switch is a network devices that is used to interconnect host devices within a LAN. Switches has multiple ports(usually up to 24) of which it can use to interconnect multiple host devices within a LAN.

A LAN is group of network devices within the same local area. For example, all the host devices exiting inside a room is usually in the same LAN. We will cover LAN in more detail later.

a lan

Although switches can interconnect host devices within a LAN, they can’t provide connectivity to the internet or another LAN. To connect the host devices within a LAN to the internet, we need a router.

4. Router

A router is a network devices used to forward traffic from one LAN to another. When a host device within a LAN want to communicate over the internet or to a host device in another LAN. It will send its request to the router which will now forward the request to the internet or to the second LAN. This router also helps to forward the reply from the internet back to the PC.

A wide area network

Unlike switches, a router has a smaller number of network interfaces (ports). This is because it is not designed to interconnect multiple devices like a switch.

5. Firewall

A firewall is a specialty network security device that is used to control traffic entering or exiting a network. It can be placed outside of a network or inside it. What is important is that it protects the host devices within a network.

A firewall should be configured with security rules to determine which traffic should be allowed or denied. This rule is such that it blocks any network traffic from an attacker.

a network topology comprising of a firewall, a hacker and router

The firewalls that we have demonstrated in the network topology above are network firewalls. Network firewalls are firewalls that filter traffic between networks.

There is another type of firewall called host-based firewalls. Host-based firewalls are software applications that filter traffic entering or exiting a host machine, like a laptop.


This is where we will drop it on network devices. Although we have not covered all network devices that you will encounter in studying for CCNA, the ones we have covered are the basics, and you will learn about others as we proceed with this course.

Now, take the quiz below to test your understanding of Network devices;

Quiz on Network Devices

Practice Lab

Because this topic does not involve any configuration or troubleshooting, there is no practice lab for this lecture.

Henceforth, we will be making use of packet tracer, a simulation software that allows us to emulate networks. Your exercise is to download the software from this website and try installing it on your laptop.

In the next lecture, I will show you how to download and install packet tracer and then give a basic tutorial on how to use it.

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