Application Layer Protocols in Computer Network
FTP (File Transfer Protocol)
- FTP is File Transfer Protocol.
- It used to exchange files on the internet.
- To enable the data transfer FTP uses TCP/IP, FTP is most commonly used to upload and download files from the internet.
- FTP can be invoked from the command prompt or some graphical user interface.
- FTP also allows to update (delete, rename, move, and copy) files at a server.
- It uses a reserved port no 21.
- Dynamic Host Configuration Protocol (DHCP) is used assigning IP addresses to computers in a network.
- The IP addresses are assigned dynamically.
- Certainly, using DHCP, the computer will have a different IP address every time it is connected to the network.
- In some cases the IP address may change even when the computer is in network.
- This means that DHCP leases out the IP address to the computer for sometime.
- Clear advantage of DHCP is that the software can be used to manage IP address rather than the administrator.
- The Hypertext Transfer Protocol (HTTP) is used to access the data on WWW(World Wide Web).
- The functions of HTTP are the combination of FTP (File Transfer Protocol) and SMTP (Simple Mail Transfer Protocol).
- HTTP is similar to FTP, because it uses only one TCP connection (data is transferred between Client and Sever).
- In SMTP, the messages are stored and then forwarded to the destination, but the HTTP messages are delivered immediately.
- HTTP uses the services of TCP on well-known port 80.
- It is an application layer protocol, which can be used on the internet or LAN(Local Area Network).
- It provides a bi-directional interactive text oriented communication service by using virtual terminal connection.
- Telnet is basically a client server protocol, which is based on a reliable connection- oriented transport.
- It uses a port number 23, to establish the connection with TCP (Transmission Control Protocol).
SMTP (Simple Mail Transport Protocol)
- It is an internet standard for e-mail Transmission.
- SMTP connections are secured with SSL (Secure Socket Layer).
- In SMTP, the messages are stored and then forwarded to the destination.
- SMTP uses a port number 25 of TCP.