TCP (Transmission Control Protocol)

TCP/IP Transport Layer's TCP provides guarantee Delivery of Data.

• HTTP was built to get a Web page from a Web Server for a Web Browser. If however the page is lost in between then the lower Layer's (Transport Layer's) TCP provides a Guarantee Delivery error recovery feature with the help of Re-Transmission & Acknowledgment.

• Each TCP Headers (encapsulated by Transport Layer) include Sequence Numbers & if a PC's Web Browser receives a response from a Web Server with Seq Numbers 1,3 & 4 it will automatically send a re-transmission request of a 2nd missing Segment thereby providing guaranteed delivery of Data.

Reference:

CCNA 200-301 OCG, Volume 1, Pg. 20-21 - Wendell Odom .