Just a quick post on something that was not immediately obvious when it happened to me.
When deploying vCSA 5.5 and trying to add it to the domain, I was presented with the following error.
I immediately did all the all the usual checks, making sure it had a static IP and correct DNS servers etc..
The one thing missing however was a FQDN for the hostname (in the network tab).
All I had was “vCSAname”
But what was required to join a domain was “vCSAname.domain.local”
After I applied this change the vCSA connected to the domain without a problem.
As always with these niggles its simple when you know how!