What service uses UDP port 242? According to nmap, it says that the service or protocol named "direct" uses the port, but Google search does not seem to bring me an answer.
It was once assigned to Herb Sutter for Peer-Direct (PDRE). Peer-Direct was an application to replicate databases. UDP and TCP ports are assigned together, but PDRE never used UDP for any purpose. So it is basically free for anyone to use for any purpose.
Any service could use it. No service that I know of typically uses it.