Question

Which of the following is not an application layer service?

(a) Network virtual terminal

(b) File transfer, access, and management

(c) Mail service

(d) Error control

I have been asked this question in an interview.

My question is based upon Packet Switching & Circuit Switching in chapter Security & Physical Layer of Computer Network

Answer 1

Correct answer is (d) Error control

To elaborate: Application layer is the topmost layer in the OSI model. Network virtual terminal, mail service, file transfer, access and management are all services of the application layer. It uses protocols like HTTP, FTP, and DNS etc. to provide these services.