TCP is one of those protocol, and it can run on top of IP datagrams (as is done typically) or UDP datagrams, in the case of applications like MixApp that don't want to use the operating system's ...

Performance Analysis of TCP and UDP Using OPNET Simulator. ... From the hottest programming languages to commentary on the Linux OS, get the developer and open source news and tips you need to know.

If it uses the UDP protocol to send and receive data, it will use a UDP port. Figure 1, below, is a represenation of an IP address split into its many TCP and UDP ports.

If a UDP port 53 response is larger than 512 bytes then it may be truncated or then DNS falls back to using TCP. However, if TCP is blocked on the firewall then the lookup can fail altogether.