Hi,
If you are changing the name of AIX bos, you need to update the new name of AIX box in the DNS.
May be you can add the oldname as an alias to the newname so that both names will be resolved to the AIX box.
This DNS update has to be done on the DNS Server.
After this, you can reload/refresh the DNS server so that it will respond to the name query for the new AIX boxname.
Hope this helps.