Internet Protocol (IP) and Transmission Control Protocol (TCP) are the languages computers use to communicate with each other and break the rules of the internet.
TCP/IP makes the Internet work a bit like a postal system. has an address book identity of each device (opens in new tab) a standard set of envelopes for network and data encapsulation. Envelopes should have the address of the sender, the address of the recipient and details of the information packed inside.
IP explains how the address system works, while TCP explains how data is packaged and sent.
All computers receive an IP address when they connect to the Internet PC magazine (opens in new tab), and they are all unique. You can find out your IP by typing “what is my IP” into Google. You will see that this is not very suitable for people. It contains either four digits between 0 and 255 separated by periods, or a sequence of eight four digits separated by colons.
You may also notice that your IP address does not remain the same. At home, you get your IP address from your ISP, but when you’re out and about, it might come from the Wi-Fi you’re connected to at a coffee shop or your company network. Business Insider (opens in new tab).
How TCP/IP works
In order to download a website, your machine needs to know the IP address of the web server that contains the data. It can also be a long string of letters and numbers and change unexpectedly.
Fortunately, there is a second addressing system that helps you point your computer to the right place. Known as the Domain Name System, or DNS for short, it gives servers names that correspond to people called domains. Cloudflare (opens in new tab). Your web browser can look them up to find out which IP address to use.
Your computer can then communicate with the server using a three-way handshake CISSP Study Guide (opens in new tab). First, it sends a message to the server asking if it is ready to talk. He called it “synchronization?” by sending an empty envelope containing the word written in front of it.
If the server is ready, it writes “confirm” on the new envelope and sends it back. Finally, your computer completes the connection by sending a third envelope that says “submit.”
Now you are ready to start exchanging data.
To do this, the server divides the content of the website into small pieces and wraps each in its own envelope. Externally, it writes its IP address, your IP address, and your serial number Cloudflare (opens in new tab). This figure tells your computer how to connect the pieces.
When your computer receives one of the envelopes, it checks it and sends back a message: “submit.” It means “I got the data and everything looks good”.
If the server does not receive an acknowledgment after a certain amount of time has passed, it assumes the envelope is lost or damaged and resends it. IR Technologies (opens in new tab).
Once all the data is safely on your computer, the only thing left to do is close the connection. This is another three-way handshake. A computer sends an envelope: “finish”. Another sends back: “submit.” The first responds: “submit” and the connection is closed.
Additional resources
Check out the many resources at the Internet Society for more information on how the Internet works (opens in new tab) and “Accessing the Net: How the Internet Works (opens in new tab)” By DR. Charles R Severance.
Bibliography
- Eric Conrad, et al, “CISSP Study Guide (Second Edition) (opens in new tab)“, Singres, 2012.
- IR Media, “What is Network Packet Loss? (opens in new tab)“, accessed April 2022.
- Cloudflare, “What is DNS? | How DNS works (opens in new tab)“, accessed April 2022.
- Cloudflare, “What is TCP/IP? (opens in new tab)“, accessed April 2022.
- Dave Johnson, How to change your IP address to fix problems with your Internet connection or protect your privacy (opens in new tab)” Business Insider, May 2021.