Question

What is the Application Layer and what does it do?

(Please explain in details with simple words).

Answer 1

The topmost layer/Layer 7 in OSI(open system interconnection) model is the Application layer.

In Application layer the user has access to the network applications like email, file transfer, web browsing etc.

Some of the common applications that run at the application layer are:- SMTP(simple mail transfer protocol), Http(hypertext transfer protocol), FTP(file transfer protocol), TELNET , DNS(Domain name system).

SMTP is used for transfer of email messages.

FTP is used for transfer files between two end system.

For delivering data in world wide web HTTP protocol is used which is a TCP IP based.

DNS is used for mapping domain name into IP.

TELNET is used for remote logging.

If we talk about end users so they directly interact with the application layer. The main role of application layer is to provide the protocols for the softwares to send and receive the information to the end users.