Using a DNS name is preferred to using an IP address in VoIP Detective.  This is primarily because licensing is tied to site URL, and using a DNS name guarantees that it will be unique.  If you use a DNS name for the "Site URL" of VoIP Detective, but fail to set the DNS name in the CLI, VoIP Detective will end up not responding to calls to itself.  This makes setting the DNS name very important.

Setting the hostname on your VoIP Detective installation

The hostname for VoIP Detective is set through the CLI.  You can use SSH, or the VMware console, and login.  The default credentials are username cliadmin  password voip.

Choose the option to configure network settings, and you are presented with this menu

Be sure to reboot the virtual machine to apply any changes.