It’s a review of “Introduction to Networking” by Charles Severance.
This book is a valuable source of information for all those who want to understand how the Internet works. The Internet is a global network of computers. It is beneficial to know the basics, especially in today’s world where everything is wirelessly connected.
How do computers communicate?
Every computer connected to the Internet has an IP address. If the connection comes from LAN (Local area network – multiple computers connected at one location), the IP is permanent. If you connect through Internet Service Provider, you get a temporary IP address. How do computers communicate? If someone wants to send you a long message, it is divided into packets (chunks of data) before it arrives at the destination. These packets go down through seven layers respectively: application, presentation, session, transport, network, data link and physical layer. Next, when the packets reach the destination computer, they work their way upwards the seven layers mentioned earlier.
Physical Layer ensures that the initial connection has been established. Multiple computers connected to a networking device on the LAN can easily communicate with each other. The message you are sending to someone is divided into packets and these ‘chunks of data’ travel (they move through routers) independently and sometimes out of order. They know where to go because before they left the ‘sending’ computer, they were added a prefix that included MAC address (Media Access Control) alongside other data. MAC is a unique identifier (a number) that is assigned in hardware to NIC (Network Interface Controller). Every computer has MAC address.
Web browsers and websites
If the communication is to be useful, a computer needs to follow a set of rules. It is where protocols come into play. HTTP (Hypertext Transfer Protocol) and IP (Internet Protocol) are examples of the networking protocols that enable you to view a particular website. How does it work? If you want to browse a page, you type its address in a browser address bar. The browser that you are using (Internet Explorer, Mozilla Firefox, Google Chrome etc.) sends a request to a server where the website’s data are stored. The server sends the requested data to the browser and the latter displays them for you to see.
A transport layer is a group of protocols that provide services to the application layer protocols. Lower layers always provide services to the layers above them. For example, when your web browser requests data from the server, it needs to deliver them to you. What if some get lost along the way? The transport layer’s TCP (transmission control protocol) monitors the transmission and checks whether data successfully arrived at their destination.
URL (Universal Resource Locator) has a structure. For example, the commonly called web address http://www.digitalmediafacts.com contains four major parts (scheme, host, path, query string). The first one indicates the protocol (HTTP). And, the second one includes the hostname of the web server. Your computer requests IP address from DNS (Domain name server). Next, your web browser makes a request to the web server, and if all goes well it receives the files. Then, the browser displays them to you.
All in all, the book describes well how computers communicate over the Internet. It is a basic introduction for anyone who wants to understand the concept of networking. I highly recommend that you check this book. Also, if you think I omitted something in my post that would be worth mentioning, let me know in the comments below! I am open to any corrections or suggestions. Thank you for reading!