Symptoms:
VMware vCenter Server
VMware ESXi
This issue occurs if the virtual machine Configuration Parameter isolation.tools.setinfo.disable is set to True. When configured this way, the guest operating system does not pass IP Address and DNS Name information to the ESXi/ESX host for display in vCenter Server. Newly created virtual machines without this virtual machine Configuration Parameter set to True do not exhibit this problem.
Note: It is not required for the vCenter Server to be apart of the domain for the fully qualified domain name of a managed virtual machine to be displayed; however, if the virtual machine is not member of domain, then DNS name on virtual machine's Summary tab will display the hostname only.