If you encountered problems with your XenServer host not able to resolve any hostnames, but know that its network and DNS servers are working properly, then it could be that you need to add the DNS search suffix in your environment.
First to see if this is indeed the problem, go to the XenServer host’s console and check your /etc/resolv.conf file. Add the search suffix to the file, for example “search your.domain.com”, like the following:
Once you added the search suffix, save the file and trying pinging the hostnames in your network. If it’s working then you have fixed the problem. However, adding the entry in resolv.conf file is only temporary. When you reboot the server, a new file will be created and the entry will be gone. To make it permanent, follow the instructions in this CTX article.