Is it possible to setup some DNS server where it will default to an IP address if the the host name it tries to resolve fails to resolve? I'm having a problem where a host name is intermittently failing to resolve.
What is the output of NSlookup? What are you using for a local DNS server? Who do you forward to? Have you cleared your cache (both server side and client side)?
Depending on the error with NSlookup, try specifying a different server - maybe Google's DNS servers 126.96.36.199 an see if there is a difference.
also more details about what you are trying to do when you start having problems would be helpful..