TCP(Transport Control Protocol) handshake

In networking TCP handshakes are very very important .

Typically our web browser talks for use with the servers. when we type a url or a domain in the search engine then first DNS lookup is happend .

What is DNS lookup?

DNS lookup is the process where the os gets the IP address from the internet for https://example.com . In this process the web browser first cheks it's cach for the domain if not found then it tells the os to find it same as os searchs for the ip if not found then it reuests the RESOLVER for the IP if not found in the cache then the req is sent to the ROOT again if not found in the cache then it sends the req to the TLD (here .COM) if TLD also not found it then it sends the req to the Authoriative ( like ns1.example.com ) finally it returns the ip address

Then the Three-Way-TCP-Handshake is done

How it's done ?

First the initiator ( typically the browser ) sends an SYN (SYNchronize req) packet to the other host or web server ( here example.com’s server) then the server rensponds and send back a SYN-ACK (SYNchronize-ACKnowledge) receving the SYN-ACK packet finally the initiator sends an ACKnowledge and finally the TCP handshake or socket connection is established.

That's what a TCP handshake is