Why do some servers have TCP/UDP alongside the port they're listening to. To my understanding TCP and UDP are socket layers, they're methods of determining how the traffic is being sent over the network, so why would this be relevant when sending a request to a server. The port number should represent the process such as FTP, and when the client connects I should be able to choose TCP or UDP, depending on how I want the data transferred.
So why so some ports force a socket layer protocol?