Application Layer and Transport Layer Protocols

• The application layer is an abstraction layer that sits on top of the transport layer.
• Application layer protocols use the underlying transport layer protocols to establish host-to-host connections.
• For example, World-Wide-Web servers operate on port 80, and email relay servers usually listen on port 25.
• TCP is used for reliable, ordered data transfers, while UDP is used for less reliable, unordered data transfers.
• UDP lacks built-in network congestion avoidance, and so must be carefully designed to prevent network collapse.

Test your knowledge of the relationship between the application layer and transport layer protocols, as well as their functions and characteristics. This quiz covers topics such as host-to-host connections, port numbers, and the use of TCP and UDP for data transfers.