Features and protocols at each level of the TCP/IP model

Hierarchy name	function	Agreement
Application tier (Application layer)	Responsible for implementing all application-related functions, corresponding to the upper three layers of the OSI reference Model	FTP (File Transfer Protocol) HTTP (Hypertext Transfer Protocol) DNS (domain Name Server protocol) SMTP (Simple Mail Transfer Protocol) NFS (Network File System protocol)
The Transport layer (Transport layer)	Responsible for providing reliable transport services, corresponding to the fourth layer of the OSI Reference Model	TCP (Control Transport Protocol) UDP (User Datagram Protocol)
Internetwork (inter-network layer)	Responsible for addressing and data transmission between networks, corresponding to the third layer of the OSI Reference Model	IP (Internet Protocol) ICMP (Internet Control Message Protocol) ARP (Address Resolution Protocol) RARP (Reverse Address Resolution Protocol)
Network interface (Host-to-net Layer)	Responsible for the transmission of actual data, corresponding to the next two layers of the OSI reference Model	HDLC (Advanced Link Control Protocol) PPP (Point-to-Point Protocol) SLIP (Serial Line Interface protocol)

Features and protocols at each level of the TCP/IP model