I have been spending quite a bit of time in the lab lately (researching, prototyping, breaking things, etc.) and one of the challenges I have is figuring out which environment I am actually logged into. I literally have a dozen VCSA (vCenter Server Appliances) deployed for various testing and I always forget the build and release the system I am currently logged into. A quick way to get this information on your VCSA is to run the following command:
vpxd -v
Note: There is also vpxd.exe for vCenter Server running on Windows which you can also use.
I also noticed in the VCSA 5.1 it used to provide the vCenter Server build and release number when SSH into the host but it looks like this has now changed with the VCSA 5.5 release. I suspect this might be related to some of the security hardening that has been done by VMware on our appliances (which is great) and I assume there maybe an issue by providing the build and version info as part of the SSH banner.
If you wish to re-enable this feature, you can just edit the /etc/ssh/sshd_config and specify the banner to point to /etc/ssh/banner which will includes both the release and build information. In any case, if you are in a pinch and need to quickly figure out the version, you can use the command above.