Role of OSI application layer

Answer 1

Think in terms of HTTP (HyperText transfer protocol), FTP (file transfer protocol), DNS (domain name services) and DHCP (dynamic host configuration protocol).

The application layer is the highest level, layer 7 of the OSI an ISO (International Standards Organization) (Open Systems Interconnect) model. ISO falls under the ANSI (American National standards Organization). This is an old standard and I believe the layers have been redefined once or twice over the years. Generally you can think of the application layer as what is on the screen in front of you. If you download a web page, open an email or get an IM (instant message) from someone you are looking at the application layer. Remember that the presentation layer 6 just below application may have done some data formatting, decrypting or conversion of some kind before the data is actually visible at the application layer.

Clear as mud?

Answer 2

The application layer is the topmost layer on the OSI model. It provides the interface to the network applications and services.