A network operates with the help of networking devices like switches, access points, routers and in some cases hub.
These devices are the important networking basics that allow computers or equipment in the network to communicate with each other and with some other networks.
Computer networks have now become an important part of a business, academics and for individuals.
Everyone uses the network either for research, email or just to communicate with a friend or relative.
From the above explanation, we can define a computer network as a group of computers or devices (printers, scanners etc.) connected together by networking devices (switch, Router etc.) and transmission media (cable, wireless etc.) and are able to share resources.
- 1 Brief History of Computer Network
- 2 Networking Basics: Advantages of a Computer Network
- 3 Networking Devices
- 4 Network Architecture
- 5 IP Address
- 6 Ports
- 7 NAT
- 8 DHCP
- 9 Protocols
- 10 TCP
- 11 UDP
- 12 Differences between Workgroup, Home group And Domain Networks
- 13 Types Of Network
- 14 Network Layer
- 15 Network Topology
- 16 Requirements for a Network
- 17 A Dummy Guide to Networking
- 18 Home Network
- 19 Wireless Network
- 20 Computer network security
- 21 Free computer networks book In PDF
- 22 computer networking courses
Brief History of Computer Network
The concept computer networking started many years ago and as time passes, it’s getting cheaper and faster.
You will learn about some important dates in the history of computer network.
It all started in the 1950s when military radar called SAGE (Semi-Automatic Ground Environment) was developed.
Intergalactic Computer Network was developed by J.C.R Licklider in the year 1962. It is from this computer network that the ARPANET was developed.
During the year 1976, a network that can share storage devices was created by John Murphy.
In the year 1995, there is an increase in the transmission speed of Ethernet to 100Mbits/s from the previous 10 Mbits/s.
This development didn’t stop there, gigabit Ethernet transmission was developed in 1998. In 2016, it increased to 100 Gbits/s.
One of the major reason why Ethernet is still in use today is because of its increase in transmission speed.
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Networking Basics: Advantages of a Computer Network
The main reason of networking is to share resources like
Devices (Printers etc.)
Internet and internet services like email etc.
Network Interface Cards (NIC)
Network interface cards also known as network cards helps to physically connect the computer to the network.
This card is located on the motherboard of each computer.
It converts the files or data from a computer into electrical signals before sending it to the network.
The function of Repeater/Hub is to receive network signal, remove any unwanted noise from it and amplify/regenerate the signal to its output.
Repeater and Hub work in the same way the only difference between this two is that a hub usually has many ports. In other words, a hub is a repeater with many ports.
The repeater will regenerate the incoming signal to its single output port while a hub will regenerate the signal to all its ports.
One of the common problems associated with this device is that it takes some time for it to regenerate the signal as a result of this, propagation delay occurs which in turn reduces the performance of the network.
These two devices are not common in modern day networks another device (switch) is now used instead.
A switch (an important component for you networking basics ) allows devices like computers, printers etc. to be connected together and share resources among each other.
When computer one and two are sharing resources, computer three cannot see what they are doing.
The communication between a set of devices those not interfere the communication with another set of devices.
Switch only send data to the intended destination, unlike a hub that sends the data to all its ports.
This is possible because whenever a new device is connected to the switch, it stores the MAC (Media Access Control) address of the device.
A switch is of two types, Managed and Unmanaged.
Provides more flexibility to the network.
It can be managed and controlled from anywhere.
A managed switch has some security features and you can also program it.
on the other hand, is like plug and play devices and those not need any changes for it to work.
It is usually small in size and easy to use.
This is the kind of switch you will find in most small and home networking.
Further Reading: Network Switch
Routers usually come handy when you need to connect many networks together.
This device is responsible for getting rid of the difficult works.
Router decides what to do with an incoming packet.
When router receives a message, it will check and repack it and pass it on to the next network.
With the help of a router, you can communicate to the internet and guide against any threat that comes your way.
Some of the things a router will do for you is NAT (Network Address Translation), DHCP (Dynamic Host Configuration Protocol) and Firewall.
NAT is the process of changing your private IP address into public IP address whenever you surf the internet.
DHCP is an automatic way of assigning IP address to devices connected to the network, this is very useful when you want to connect many devices to the network.
A firewall is a security software that comes with most routers, it is used to prevent malicious messages from coming into the network.
Access points allow wireless devices to be connected to the network, it makes network connection easier and flexible. With the help of access points, you can make your LAN network available for wireless devices including mobiles.
Access points amplify the network coming from a router, provide useful information about the devices on the network and also give some security features to the connected devices.
The word MODEM is gotten from these two words MOdulation DEModulation. It converts the digital signal from a computer into analog signals so as to be able to travel on phone lines.
You can the modems as a dial-up for LAN or to link up with your ISP. There are internal and external modems. Internal ones are located in your computer system, while the external ones are connected to your system through the USB port or other related ports.
This simply describes the design and how the network is configured. It entails the strategies and the purpose of the network.
There are two other names use instead of network architecture, network design, and network model.
The two major types of network architecture are peer to peer and client/server.
Peer to Peer.
This kind of network is less expensive, simple to configure and usually contain no more than 10 computers.
is a computer network whereby the server (usually a computer with good hardware specifications) gives control access to resources be it hardware or software on the network. The server also provides centralize storage medium. The client, on the other hand, are computers that request for these resources from the server.
There are many protocols in the world of computer networking but IP address is one of the basic ones that makes the internet work.
Just like your home address that someone will use to send you a gift, it is with the help of IP address that devices can send data to one another on the network.
IP address is assigned to all the devices on the network either manually or automatically (DHCP) so that they can connect and communicate with one another.
The most popular IP address at the moment is IPV4 (IP Version 4), there is another one called IP Version 6 which is rarely used. IPV4 contains four sections which are known as octets, and each octet contains 8 bits (Binary digits).
Most of the times, a computer can only be connected to the network through one physical connection. No matter what you send to the computer, all of them will pass through that same physical connection.
But in most cases, all these data are sent to different applications on the machine. The computer makes use of the port number to determine the specific application that owns each of the data coming in.
When a data is transmitted on the internet, it carries along with it some information that indicates its port and destination computer.
The destination computer will be known with the help of 32 bits IP address, while the specific program or application that owns the data will be known by the 16-bit port number.
When a request is coming into a router, Network Address Translation (NAT) is used to translate it for the receiving device on the network. When a device wants to connect to the internet, NAT takes the IP of the device, record it and translate the IP into an external one.
When the destination machine located on the internet respond back, NAT takes the external IP and looks for the equivalent internal IP in its record then forward the response to the particular machine.
You understand that a device cannot communicate to the internet without an IP address but you wonder how you are able to surf the net with your phone or PC when you go to the restaurant or coffee shop.
The secret is that most networks, especially a Wi-Fi network, make use of DHCP, so whenever a device is connected to the network IP address is automatically assigned to the device without any delay. DHCP can be configured on both wired and wireless connection.
These are rules and guidelines that made up a language. It’s this language/protocol that devices use to communicate with one another. The number of protocols used in computer networking are many and each of them operates at a specific layer of the network.
IP, TCP, UDP are some the protocols that operate at low layers. HTTP, FTP, SSH are some of the application layer protocols that built on the low layer protocols.
TCP is only concerned with the connection because end points will have to be connected before each device begin communication. Data transmitted in this protocol is called segment. The two devices communicating within a TCP protocol inform of segments. Segments have a fixed header of 20 bytes data field with variable size.
When sending data through TCP protocol, TCP breaks the data into segments and then reconnects all the data when they get to the receiving. TCP will resend any lost segment and order all the segments accordingly at the receiving end.
UDP (User Datagram Protocol) is a network protocol that gives the communication that’s not guaranteed between the sender and receiver. The function of UDP is to send data inform of datagram and unlike TCP that make sure all the data gets to the destination, UDP does not care. All the datagrams are independent of one another.
Most applications require that all the data sent on the network should get to the other end. But some applications don’t require this kind of rules because it may slow down the communication and disturb the entire service. Take for example, during a conference call the sending end does not need to resend a lost data.
Differences between Workgroup, Home group And Domain Networks
Characteristics of A Workgroup Network
If you don’t have an account on a computer you can’t log on to that computer. All the uses of workgroup network must have accounts on all the computers on the network if they want to be using all the computers.
Computer A does not have control on computer B, also known as peer network.
No password is required to connect to a workgroup network. Just make sure you have a user account on the computer you want to use.
The number of computers in a workgroup network is usually around 20 in number.
All the computers must be connected together on the same LAN
Characteristics of A Domain Network
A domain network has a server that controls all the connected computers
It is this same server that will control permissions and security on the network.
Before you can access the domain, you must provide a username and password.
The beauty of domain network is that any user can use all the computers on the network without having a local account on the computers.
You can’t just do whatever you want on any of the computers because they are restricted. For example, it is only the admin that can install a program on any of the computers.
The number of computers on a domain network can be as many as possible.
It is not a must for all the computers to be on the same local network.
Characteristics of A Home-Group Network
Homegroup network facilitates easy sharing of resources and file within the home.
You can’t just bring your computer and connect to the network straightaway, you must provide a password when joining the homegroup network.
Any of the computers in your home can be on Homegroup network and at the same time be on workgroup network.
Each computer on the network can share a lot of things with other computers on the homegroup network.
Types Of Network
PAN stands for Personal Area Network. Just like the name, it does not exceed the individual and the device. Some the devices common in this kind of network are mobile phones, video games, PC, Printers etc. The network range of PAN is 10 meters and the devices can be connected through wired or wireless. The major devices use in wired PAN are USB and FireWire. In the case of wireless PAN, Infrared and Bluetooth are used.
The kind of network you will find in a campus or within a single building is LAN. Local Area Network does not usually exceed a specific geographical area. It can be the network between two computers and it can also be the network between hundreds of computers.
You can connect to a LAN network without a cable with the help of WLAN (Wireless LAN), an important form of LAN that allows easy connection and mobility. Do you need to access any of the resources on the network and you can’t connect to the network using a cable? You don’t have any problem if your device is having Wi-fi and you are in the WLAN coverage area.
Wide Area Network is used to connect devices that located in far distances apart. It consists of various LANs connected together by a router.
A good example of WAN is the internet, it consists of many LAN networks that are owned by various individuals and connected together.
Internet, the most popular network, it is a network comprising of other networks and all of them are connected together using TCP/IP.
The internet is a very big WAN and most of its user’s use programs like web browsers and email clients to access the internet.
An intranet is just like the internet but only meant for organizations and it’s more secure. Intranet has been easier with the development of software that can run on browsers. This kind of network is private but uses similar tools with the internet.
An intranet is usually for an organization and some of its cooperate files can be shared with some special employees outside the organization.
Open System Interconnection Model (OSI)
This networking model specifies how different network devices from different manufacturers communicate with one another by providing a standard framework for each of the devices to follow.
This framework is known as the seven layer.
Each data sent of the network pass through these layers.
Below are the explanation and function of each OSI layers.
Layer 1 (Physical Layer)
The work of this layer is to transmit data bits from the physical layer of the source to the physical layer of the destination through the network media.
One of the mostly used technologies in this layer is the network cable.
Hubs and repeaters are the popular networking devices at this layer.
The signal supported at this layer might vary based on the network media.
When cables are used it will be electric signals etc.
Layer 2 (Data Link Layer)
This layer helps to decode and encode the data passing through the network.
It corrects any error on the data with the help of the transmission protocols.
Media Access Control (MAC) and Logical Link Control (LLC) are the two sub-layers associated with this layer.
MAC controls how computers on the network access and transmit data while LLC is for error checking, flow control, and to synchronize frames.
Layer 3 (Network Layer)
This layer is responsible for the management of network and host address, it controls the subnetwork and internetwork.
The network layer route packet from one network to the other and also control the mapping of address and protocols.
Layer 4 (Transport Layer)
The main function of this layer is to ensure that reliable connection is made between the layers above and the layers below. It verifies that the data sent from the source gets to the destination intact.
Layer 5 (Session Layer)
This layer deals with the sequence that initiates and terminate network connection. The session layer is built in a way that it can support many connections and also run on many networks.
Layer 6 (Presentation Layer)
It is in this layer that data is being translated between the application and the network. This layer changes the data to the format which the network and application layer will understand irrespective of the format or encryption.
Layer 7 (Application Layer)
The communication process begins from the application layer. Because this layer is at the top of the OSI layers, it does not work for any of the other layers, all the works will be transferred to lower layers. All the other layers help the application layer to get the data across to the destination.
This is how nodes and links are arranged in a network. Any device that is active on the network is a node e.g. computer, switch, hub, printer etc. The two most popular network topologies are star and bus. These two give a good example of the way each node is connected to another on the network.
This is a series connection of nodes whereby each node is linked to the next node with a cable. With this connection, other nodes can connect to the network in the same way and communicate with one another. The main problem with this topology is that when a break occurs in any part of the cable, the nodes in that segment will not be able to communicate until the cable is repaired.
There will be a centralized device like switch, hub or even a router then all other nodes like computer and printer will be connected to this centralize device. This is the kind of topology you will see in most homes. If this centralize device is down, then the whole will be down until.
Just from the name, a node will be connected to the next node either by the right or left. an individual node can communicate with another node by sending data to its right or left. This does not make use of a centralized hub or switch.
The internet is the best way to explain a mesh topology in the sense that a node has many paths to reach other nodes on the network. This is called routing where data sent on the network will have various paths to get to its destination.
This is the hierarchical connection of nodes on the network. This is not a very common topology.
Requirements for a Network
Have you ever asked yourself this question, “What are the basic things I must have to create a computer network?”
You don’t need a complex equipment to set a network, the basic thing you need are explained below.
A network protocol which serves as the communication rule between the devices you will connect together.
Before any computer or other devices on the network can access a shared resource or file they must be a software that will make this resources or file available on the network. A good example of this software id the operating system on your computer be it Windows, Linux, or Mac OS.
Another good thing your OS can do apart from being the software that will make the file available on the network it this same software that makes systems acting like a client on the network access any shared resources.
What You Want To Share
Since you know that the essence of a network is to share resources. That means these resources are also part of the network requirement. Examples of these resources are modem – to share the internet connection, printers, and drives for file storage and so on.
A Dummy Guide to Networking
Now that you have all the networking basics in your head, just like every other field of life, some part will be easier to do than others and it is a fact that most people will want something that will just outline the how they will set up a network quickly. Something like a dummy guide.
Do you want to set up a network at your workplace or in your home?
The steps below can make the whole thing easy.
The primary aim of most computer network is to share an internet connection and if you can share this, you can share every other thing.
First, you will have to connect your router and your modem together.
Some routers do come with a built in access point for sharing for share network with Wi-Fi enabled device.
If your router is not this type and you need to connect a wireless device, then you have to get an access point and connect it to your router.
Most routers do come with LAN ports so you can connect your computers directly to it or you can use a switch to share the network for many computers.
This just the simple way of creating a computer network.
Don’t just go to the computer accessories shop and get anything networking you lay your hands on, you have to figure out the kind of network you want and most importantly what you intend to do with the network. This simple idea will save you a ton of money and also help on how to build the appropriate network for your home.
Which Network Infrastructure do you want?
Is it Wi-Fi (Wireless), Ethernet (wired) or Home Plug.
These are the basic networking infrastructures you can use.
The first and second options are most popular types and in some cases, you can use all three in a network.
Computer Networking Jargons
In the field of networking, most experts including service providers and manufacturers communicate using technical jargon it will be a good idea if you can understand some of these technical terms.
With the home users in mind, the companies that manufacture these networking devices are improving on how to make their products more consumer friendly.
The fact is that not everybody will have the access to tech expert or networking guru when setting up a home network.
Home Network Setup
Now that you have gotten the kinds of network devices that suit the network want and you have determined the infrastructure you want to implement; the next step is to the actual setup.
Read the dummy guide to networking section to get the idea of how to set up a home network.
If you have a problem or even a question about setup or any of the equipment, feel free to contact the manufacturers, your Internet Service Provider or the nearest tech support team.
Check out setting up a wireless network section as well.
These people will be more than ready to help you.
We all get into one or two problems once in a while and the honest truth about this is that the more you encounter a problem and find a way to solve it, the more your knowledge will increase.
When you hear about wireless network you can easily understand that it a connection that does use a wire (cable) to link computer, but at the same time you might wonder “what is now connecting these computers?”.
The answer to this question is that there they are connected together with help of radio frequency (RF) that we cannot see.
This idea is the same with mobile networks, and it helps a lot because you will not need to go true the stress of making cables, working it through the building and so on.
If you are following from the beginning of this page you will know that the wireless connection takes place at the physical layer (Layer 1) of OSI model.
Types of wireless network
Wireless PAN (Personal Area Network)
Wireless LAN (Local Area Network)
Wireless ad hoc network also known as wireless mesh network
Wireless MAN (Metropolitan Arear Network)
Wireless WAN (Wide Area Network)
Cellular network (mobile network)
GAN (Global Area Network) for supporting mobile
Space network (used by spacecraft to communicate usually within earth)
Wireless network advantages and disadvantages
One of the most important reasons why a lot of us like a wireless network is because of mobility. In a wireless network, you can move about with your mobile phone and laptop and still be connected to the network. Wired network, on the other hand, does provide this freedom of movement to its users.
Another advantage of a wireless network is its cost, you don’t need many devices to set up this network, and you don’t need a hell of cables. Due to few and cables, the stress and cost of maintenance is also reduced. The wireless network is less costly than a cable network.
Adding a New User To The Network Is Easy
It is very easy to add a new user to a wireless network you just have to switch on the Wi-Fi on the device you want to connect to the network and provide the wireless network password. The case will be different on a wired network and you tend to face even more work if the device you want to connect to the network is in another room or building.
If you are used to these two networks, you will notice that the speed of communication in a cable network is faster than a wireless network. And you know what? The further you distance from the router, the more the speed will reduce. This is one of the challenges faced in a wireless network especially in a large building.
Since anybody can connect to the network easily there is a high chance of intruders getting into the network particularly a network that is not protected with a password. It is very easy to attack a wireless network than a wired network.
High Rate of Interference
The devices in a wireless network communicate through radio frequency and as a result of these, the communication is prone to interference. It is not that there is zero interference in a cable network, no, it is greater in a wireless network.
Setting up a wireless network
When some people hear about setting up a wireless network they feel like “whoa you are a guru” but the truth is that wireless network is quite easy to set up.
You might think that there are a lot of things involved but it isn’t, just some few steps and you are done.
Read the networking tips below to set up your home wireless network.
What you will need
Wireless router, computer with Wi-Fi, modem and some networking cables.
You can buy all these items online including the cables.
Position the Router
If you read the advantages and disadvantages of wireless network above you will know that it is good to position the router within the reach of all users.
In a home, the best place to put the router will be the center of your home.
In this case, the signal strength will not be stronger in one part and be weaker in another part.
Some other few tips to put in mind while looking for a place to position your router is that you should not place the router on the floor.
Try as much as possible not to place the router where a wall or any physical object will be between the router and the devices that will connect to the network.
Putting Everything Together
Make sure that your router and modem are powered off.
Connect the modem to the router’s WAN port and then power the modem on.
After powering on the modem, you have to wait for few minutes before you power on the router, this will also require some few minutes because it will need to boot just like your computer system.
When the modem and the router are connected together then you can connect your computer to the router’s LAN port using an Ethernet cable.
One of the adjustments made to new routers is the default DHCP configuration which means that after you connect the modem to the router and the computer to the router, you should be online without doing the manual process of assigning IP address.
Before you give access to another person on the network, remember to change the default name of your wireless network, give it a new SSID (name of your network).
After the SSID the next thing is the password, this is very important and make sure you write it down on a paper and keep it safe.
Now that everything is up and running, add another computer to the network.
Switch on the Wi-Fi of the computer, look at the right-hand side of the taskbar to locate the Wi-Fi icon, click on it and select your network (SSID).
Provide your password and you are done.
Computer network security
What is network security?
Network security is like a body containing the practices use to prevent unauthorized access to the network, misuse of network resources and preventing the user from accessing a specific resource on the network.
Security is very important and must be part of a network setup.
There are many types of network security below are few of the basic and easiest ones.
We all know what a password is the only thing you have to keep in mind is how strong the password should be.
You can’t just put 1234 and think that’s a password. No.
It does not take you anything to use a strong password on all your network devices just make sure to write them down in a secure place.
One funny thing that most network administrators do is the mistake of using default password on the router.
This is a simple thing but it can be disastrous, change the default password on all device.
A default password is known by everybody and the question is “do you want everybody to access your network?”
Make sure you have a good reason before telling someone your password, don’t make the password too cheap.
Another tip is to create a guest account so that any visitor can use the network and change any password that is widely known by everyone in the house.
Have you seen the IT office of any big company before?
You will notice that their network devices including servers are kept in very secure place at times you will see human securities guarding the place.
In a home network you don’t need that but at least put the devices in a place that is very secure and keep in mind that the router should be at the center of your home.
Free computer networks book In PDF
Do you want any book on computer networking?
Feel free to check the sites below but know that you cannot find most good books for free and most of them are pretty cheap at Amazon.
computer networking courses
You can take computer networking courses from authorized training centers for global Networking and IT Security giants like Cisco, Microsoft, and EC-Council.
Look for those that give certifications and training programs from entry level to expert levels, laying importance on advanced infrastructure and quality delivery.
Some of the well-known basic courses are CompTIA network+, CCNA, and CCNP. From there you can get CompTIA Security+ and/or CCIE.
If you want to study computer network security fully then you can get certified in some EC-Council courses like CEH, ECSA, CSCU, and CHFI.
All of these are good computer networking certifications that will help you in any networking jobs.
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