This document provides information about a problem where the system is unable to resolve a TCP/IP address by name when the name should resolve with DNS.
Resolving the problem
Problem: Resolution by name is unsuccessful when the name is defined in the DNS.
Resolution: A communications trace revealed that an ICMP message type destination is unreachable. The code port that is unreachable is returned for the DNS query. The trace shows that the well known port (port 53) for DNS is replaced by an unassigned port number. Using the command CHGTCPDMN PORT(53) to change the remote port for the DNS back to the well-known port resolved the problem.