Protocols in Application of Layer

 Application layer protocols are those protocols utilized at the application layer of the OSI (Open Systems Interconnection) and TCP/IP models. They facilitate communication and data sharing between software applications on various network devices. These protocols define the rules and standards that allow applications to interact and communicate quickly and effectively over a network.

Common Application Layer Protocols in Computer Networks

1. TELNET

TELNET Provides remote login and terminal emulation services.

Allows users to access resources of a remote server as if logged in locally.

Port Number: 23

Command:  

telnet [\\RemoteServer]

\\RemoteServer   

:Specifies the name of the server 

to which you want to connect

2. FTP

FTP stands for File Transfer Protocol. It is the protocol that actually lets us transfer files. It can facilitate this between any two machines using it. But FTP is not just a protocol but it is also a program.

FTP promotes sharing of files via remote computers with reliable and efficient data transfer.

The Port number for FTP is 20 for data and 21 for control. 

3. TFTP

TFTP is a Simplified version of FTP, suitable for quick file transfers without authentication.

Often used for transferring boot files or firmware updates.

Port: 69

Command 

tftp [ options... ] [host [port]] [-c command] 

4. NFS

NFS Allows remote systems to mount and access files over a network as if they were local.

Used for resource centralization

5. SMTP

Used for sending emails across networks.

Works with Mail Transfer Agents (MTA) for message forwarding.

Port: 25 (SMTP), also 587 for secure transmission.

Command 

MAIL FROM:<mail@abc.com?

6. LPD

Designed for printer sharing over a network.

Receives and processes print requests.

Port: 515

Command 

lpd [ -d ] [ -l ] [ -D DebugOutputFile