Simple definition
TCP check that the data is coming in the correct order.
Technical definition
Transmission Control Protocol uses sequence numbers, acknowledgements of receipt, retransmissions and flow control. A connection usually starts with a three-step handshake.
What is it used for ?
Transport communications where reliability is a priority, such as HTTPS, SMTP, RDP or SSH.
Practical example
When loading a web page, TCP retransmits a lost segment so that the received content remains complete.
Common issues
- Port blocked
- Re-Initiated connection
- Latency increased by retransmissions
- Session interrupted by intermediate equipment
Related terms
UDP · Network port · HTTPS · SMTP · Firewall
Key takeaway: This entry explains the general operation of the term. Exact settings may vary depending on software, vendors and environments.