Networks | Part 1 of 3
We live in a world that is constantly connected, for instance, news is getting to us faster, we maintain meaningful friendships online, and we even "run" errands online. Anyone who owns a mobile phone is automatically part of the Wide Area Network, or as you like to call it, the Internet. Let us start with this magnificent bird's eye view.
Glossary
Data Packet | A small unit of data that is transmitted over a network using an Internet Protocol. |
Resources | Hardware or software shared over a network, such as printers, files, or applications. |
Service Provider | A company that offers internet and telecoms to individuals or businesses. |
Wireless Router | A networking device that connects multiple devices wirelessly and assigns unique addresses. |
Standalone Computer | A computer that operates independently and not part of a network. |
Networked Computer | A computer that is connected to a network so can communicate or share resources with other computers on the same network. |
Wide Area Network | A type network that spans a large geographic area, typically connecting multiple smaller networks. |
URL | A web address that specifies the location of a resource on the internet. |
Domain Name | A human-readable name used to identify and access websites on the internet. |
Network Interface Card | Hardware component that enables a computer or other device to connect to a network. |
Modem | A device that converts digital data from a computer into analog signals for transmission over telephone or cable lines. |
Client | A computer or software application that requests services or resources from a server on a network, such as accessing web pages or downloading files. |
Server | A computer or software application that provides services or resources to clients on a network, such as hosting websites, storing files, or managing network communications. |
HTTPS | A secure extension of HTTP, the protocol used for transmitting data between a web browser and a web server over an encrypted connection. |
IP Address | A unique numerical identifier assigned to each device connected to a network, allowing devices to communicate with each other by specifying the source and destination of data packets. |
Domain Name Server | A server that translates domain names e.g., www.google.com into corresponding IP addresses, allowing computers to locate websites on the internet. |
What is a computer network?
A network is a physical connection between two or more computers to communicate and share data or resources. Remember, computers is a wide term in this case that includes many devices; desktop computers, laptops, tablets, and smartphones. All of these can be part of a network. Most probably you are fully aware you are making use of several networks. Can you relate to any of the following network examples?
Mobile Data Network Your smartphone is part of a network by your Service Provider e.g. Go Mobile, Melita and Epic Mobile.
Public Wi-Fi Network You might be in a coffee shop and you freely connect your phone to a wireless router by entering a password.
The Internet Most of the time you want to be connected to the internet of course which is the biggest network in existence, connecting other networks together over vast geographical distances. This type of network will be the focus of this post.
Networks have completely changed the way we use computers. You do not remember a time when most technological devices were standalone. To help you understand this concept, the diagram below paints a picture of the key difference between a standalone computer and a networked computer. A standalone computer is one that is not part of a network so it cannot communicate or share data with other devices! On the other hand a networked computer is one that is connected to other devices as part of a network, for example a WAN.
Wide Area Network aka Internet
In this chapter, you will learn about types of networks, some of which are illustrated in the following diagram to give you a general idea. We assumed that you are mostly familiar with internet basics, which is formally referred to as a Wide Area Network, WAN in short.
A Wide Area Network is a computer network that spans a relatively large geographical area. This is possible by creating physical connections between networks across the globe. These connections are made using leased telephone lines, high-performance cables, wireless technologies, and even satellites! The internet is the largest WAN in existence and we
are all part of it.
Advantages of WAN
Being part of this WAN gives a lot of advantages as you probably already realise.
Access to a lot of information that is distributed amongst several computers. Networked computers can access vast amounts of information regardless of geographic location. Someone in Malta can access and read a webpage hosted by someone in the United Kingdom, simply because they are connected through networks. This implies the possibility of spreading vast amounts of data across multiple devices instead of having it centralized to just one machine. Imagine if all the important data had to be kept on one machine, and then that machine suffers a hardware failure, it would be catastrophic. Spreading data across many devices on the network makes our network robust and reliable.
Accessing high-end services via SaaS We can also distribute hardware and software resources over a network which paved the way for hosting streaming services like Netflix and Disney+. Nowadays, to use a software, we rarely resort to installing a copy of the application on our physical computer, but rather access it through a web browser and a friendly URL. The user does not need to worry whether the program is compatible with their computer, or buy specific powerful hardware which is expensive and difficult to maintain.
Fast and convenient communication Through networks, we can have voice calls, and video calls, send emails, and chat. Perhaps one of the oldest communication mediums is email; a user can type up a message, attach files, and send it off to someone over multiple networks. It is fast, reliable, and very efficient.
Once again, let's think of the old standalone environment. Every computer would need to have everything on it or directly connected to it exclusively! This is too expensive and impractical. Through the internet, (or any type of network for that matter) many kinds of hardware and software resources can be shared by multiple users.
Disadvantages of WAN
That said, it's not all sunshine and roses ☔️and you are probably aware of some drawbacks of being part of the internet.
Can cause disruption when technical issues arise At times the internet can have connectivity issues, disrupting normal operations. Imagine if Google was temporarily disconnected from the WAN. We would not be able to use their search engine 😨!
Unwanted malware can also be shared We need to ensure we are safe and not accidentally download viruses 🦠 which can damage our computers and other devices we are connected to.
We are sharing the WAN with cyber criminals There is a danger of hacking 👺 so security procedures are needed to prevent such abuse e.g. implementing a firewall which is explained in Chapter 23.
Basic Network Hardware Checklist
Everything we have talked about so far does not happen by magic. We need to make sure that our devices can be on a network and we need additional hardware to connect to the internet.
What do we need to be able to have three laptops connected to the internet?
Network Interface Controller (NIC) Every device on a network must have a NIC which is also referred to as an Ethernet card or a Wi-fi adapter.
Modem We need this device to be part of the WAN through telephone or cable lines that are maintained by an Internet Service Provider or ISP in short. Its purpose is to act as an analog-digital converter.
Router When we have multiple devices on the same network we need a router which is responsible for managing the data packet traffic between the devices.
A Masterclass in Web Surfing
When we have a question we instinctively ask Google rather than asking our parents. You probably already know that you use a web browser to access data on the World Wide Web. If this concept is new to you, perhaps you should quickly read Chapter 12. In this section, we will break down a simple internet search using our favorite search engine. This simple action that we probably take for granted involves multiple computers communicating and sharing data on the same network.
1. Different roles within a computer network
Each computer within a network has a particular role to ease collaboration between computers in a network. When you are using the web browser to perform a search, the software application is taking the role of a client. A client is a piece of software or a computer that is trying to get something from another computer over a network. The computer that is probably far away from yours which is allowing you to make use of the search engine is the server owned and taken care of by Google, for example.
2. HTTPS protocol for secure communication between client and server
We are only able to trust this process blindly because both computers are obeying a set of rules to communicate effectively. The client obeyed used these rules to make a request that
the server can understand. So in turn, the server can process the request, by performing the search through its vast database. Once it filters the relevant data, it also needs to obey some rules to send a response back to the web browser, the client.
What we described simplisticly is the HyperText Transfer Protocol (HTTP), HTTPS is simply a secure extension of this standard communication between web clients and web servers. Https indicates that the communication is encrypted, meaning that any data transmitted between your web browser and the server is scrambled to protect it from being intercepted by unauthorized parties. But how do you know if the website you're visiting is legitimate and not an imposter trying to steal your information? This is where digital certificates come in. Digital certificates are like virtual ID cards that websites use to prove their authenticity. These certificates are issued by trusted organizations and contain information about the website's identity, such as its domain name, for example, https://www.google.com/. When the web browser verifies that the response is authentic it displays a padlock icon in the address bar.
3. Ensuring that the right computers get the right data
All computers that are connected to the internet must have an IP address which is like a unique phone number assigned to each device. To ensure reliable communication between computers we need to specify the source and destination of data so each device on a network is assigned a unique logical address by the router. There are two primary types of IP address formats used today IPv4, v means version, and IPv6. The key difference between the two is that IPv4 is a numerical address and IPv6 uses hexadecimal notation so that it could support a much wider range of addresses since the WAN keeps getting larger. Most of the time we use domain names to access popular websites, but these are friendly names that correspond to IP addresses. When you type a domain name into your web browser, the Domain Name System (DNS) server converts it into an IP address. IP addresses might change so this mapping ensures that you load the correct website!
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