Application layer protocols are mainly useful for communication purposes. Its used by ISP (Internet Protocol Suite) and OSI (Open Systems Interconnection). Protocols which are used in application layer are application layer protocols. Protocols in application layer are as :
1]BGP
2]DHCP
3]DNS
4]FTP
5]HTTP
6]IMAP
7]LDAP
8]MGCP
9]NNTP
10]NTP
11]POP
12]ONC/RPC
13]RTP
14]RTSP
15]RIP
16]SIP
17]SMTP
18]SNMP
19]SSH
20]Telnet .etc