netbackup unable to resolve hostname.....

Hello,

Even though your backing up a VM. NetBackup is trying to see if it can resolve the hostname of your VM. In this case it can't, so it tries for the alias if you have set up one with the bpblient command (TECH189804).

Please check and see if your NetBackup environment can resolve the VM hostname you specified in the policy. Please also check for short name VS FQDN as well. If it doesn't resolve, modify DNS or hosts file.

Have a look at Primary VM identifier in Backup options on the VMware tab.

The default is VMhostname which requires network lookup.

Have a look at Table 5-3 on p. 54 of NetBackup 7.5.0.x for VMware Administrator's Guide  http://www.symantec.com/docs/DOC5605 
See if one of the other options will work.

I must admit, this is a first for me:
"All or most of the VM's in my environment are dev, so some dont have an IP and are not routable."

You will also want to disable IP Resolution. 
See p.158 of the same manual for instructions on changing disableIPResolution in the Registry of the backup host.