SYSTEM-DESIGN
beginner
TCP 3-Way Handshake
Software Engineer path · lesson 64 of 99Animate the standard Transmission Control Protocol handshake to understand connection reliability.
TCP 3-Way Handshake
Ready to initiate TCP connection establishment
Connection-Oriented
Connecting...
Step 0/4: Ready
Client
Server
1. SYN
Client → Server
2. SYN-ACK
Server → Client
3. ACK
Client → Server
Open a connection
Sequence
Order the TCP three-way handshake.
Tap a piece, then tap where it goes — or drag it. Tap the tray to take one back.
- 1Drop a step here
- 2Drop a step here
- 3Drop a step here
- 4Drop a step here
- 5Drop a step here
5 pieces left to place
Test your knowledge
21 questions
Question 1 of 21
Score: 0
Which packet type is sent by the server to both acknowledge the client's request and establish its own sequence number?
The short version
The TCP handshake is like making a phone call: You say "Hello?" (SYN), the other person replies "Hi, I hear you, can you hear me?" (SYN-ACK), and you reply "Yes, I hear you!" (ACK). Now the conversation can begin.
In more depth
TCP (Transmission Control Protocol)
TCP is a foundational networking protocol that provides reliable, ordered, and error-checked delivery of a stream of bytes.
The Handshake Steps
1.SYN: Client sends a Synchronize packet with an initial sequence number.
2.SYN-ACK: Server acknowledges the client's sequence number and sends its own Synchronize packet.
3.ACK: Client acknowledges the server's sequence number.
Interview Questions
Amazon
Google
Cisco
Google
Meta
Cloudflare
Amazon
Netflix
Uber
Cloudflare
Google
Datadog
References & Further Reading
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