MBF Knowledge Base

Why is the CommuniGate Pro Server opening a non-standard UDP port on my system?

This is a DNR (Domain Name Resolver) socket. The port number is selected by the OS, and it can change if you restart the CommuniGate Pro Server. This socket is used to send requests (UDP packets) to DNS servers and to receive responses from those servers.

Other applications (servers, browsers, etc.) use the same type of sockets to resolve domain names, but they usually open and close those UDP sockets quickly, so you may not notice them in your netstat output. CommuniGate Pro opens the DNR UDP socket when it starts, and uses that socket for all DNR requests, closing the socket only when the Server shuts down.