Computer Networking Basics
In the four-layer TCP/IP model, which layer do TCP and UDP belong to?
- AApplication layer
- BInternet layer
- CTransport layer
Show answer and explanation
Answer: C. Transport layer
The TCP/IP model is described with four layers, from the bottom: the link layer (network interface layer), the internet layer, the transport layer and the application layer. TCP and UDP are transport-layer protocols, and they use port numbers to tell which application on a host the traffic is for. IP, in the internet layer, is responsible for delivering packets from one host to another. HTTP and DNS are application-layer protocols. Mapped onto the OSI reference model, the transport layer corresponds to layer 4 and the internet layer to layer 3.
- A. The application layer holds protocols used between applications, such as HTTP and DNS.
- B. The internet layer holds IP, which delivers packets from host to host.
- C. Correct. TCP and UDP are in the transport layer and identify applications by port number.