TCP Handshake

Have you ever wondered what happens when you type in youtube.com and press Enter? First, the DNS lookup happens. That is a fancy way of saying that your browser checks to see if it already knows where the website is.

After the DNS has been looked up, the TCP Handshake begins.

Computer

Client

TCP Handshake Diagram

Handshake

Server

Server

The steps of the TCP Handshake:

Step 1 - The Client (you) sends a SYN request to the Server (youtube.com)

Step 2 - The Server (youtube.com) responds to the Client (you) with SYN-ACK

Step 3 - The Client (you) responds with ACK