Today had error pop up on vCenter server for vpxa service in yellow state, also found that ESXi host was showing errors for “Cannot synchronize host” as well as “quick stats on is not up-of-date”

Troubleshooting:

After doing some investigation found that one of the new hosts did not have a DNS entry created.

Fix:
This should be by now a given but always test forward and reverse DNS lookup for ESXi host before adding to vCenter server!