At the top of the OSI model graphic is the application layer, or layer 7. This layer contains protocols that allow process-to-process communications, and it's where we initiate contact with the network to perform the following:

• Retrieve a web page.
• Fetch or send our email.
• Upload files to an FTP server.
• Request a dynamically assigned IP address.

On the IP network, each application layer protocol follows specific recommendations, requirements, and options, according to its function. Let's talk about a few application layer protocols along with the PDU.