HTTP
• The Hypertext Transfer Protocol (HTTP) is a Application layer protocol used mainly to access data on the World Wide Web.
• HTTP uses the services of TCP on well-known port 80.
FTP
• FTP (File Transfer Protocol) is standard TCP/IP protocol to transfer files.
• It uses the services of TCP. It needs two TCP connections.
• The well-known port 21 is used for the control connection and the well-known port 20 for the data connection.
SMTP
• It stands for Simple Mail Transfer Protocol. It is a part of the TCP/IP standard protocol.
• Using a process called “store and forward,” SMTP moves your email on and across networks.
• It works closely with something called the Mail Transfer Agent (MTA) to send your communication to the right computer and email inbox.
• Port number for SMTP is 25.
TELNET
• TELNET is an abbreviation for TErminaLNETwork. It is the standard TCP/IP protocol for virtual terminal service
• TELNET enables the establishment of a connection to a remote system in such a way that the local terminal appears to be a terminal at the remote system.
• There are two parties involved TELNET Client and TELNET server.
DNS
• It stands for Domain Name Service. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address.
• For example, the domain name www.abc.com might translate to 198.105.232.4.
• Port number for DNS is 53.
DHCP
• It stands for Dynamic Host Configuration Protocol (DHCP). It gives IP addresses to hosts.
• There is a lot of information a DHCP server can provide to a host when the host is registering for an IP address with the DHCP server.
• Port number for DHCP is 67, 68.
POP3
• Post Office Protocol, version 3 (POP3) is simple and limited in functionality.
• POP works as a Message Access Agent.
• The client POP3 software is installed on the recipient computer; the server POP3 software is installed on the mail server.
• Mail access starts with the client when the user needs to download e-mail from the mailbox on the mail server.