What is the three-way handshake in TCP?

beginner

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Answer: The three-way handshake establishes a TCP connection between client and server:

SYN: Client sends SYN packet with initial sequence number
SYN-ACK: Server responds with SYN-ACK, acknowledging client's SYN and sending its own SYN
ACK: Client acknowledges server's SYN-ACK
Example flow:

Client → Server: SYN (seq=100)
Server → Client: SYN-ACK (seq=200, ack=101)
Client → Server: ACK (seq=101, ack=201)

This ensures both sides are ready to communicate and establishes initial sequence numbers.

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