In the Help>About and Server logs is reported the build number of the version of Vault Server used.
This can help sometimes for you to confirm what version of the software is actually being used if there is some misunderstanding or miscommunication with the servers Administrator.
For example if they are trying to log in Vault 2009 from a Vault 2010 client. Looking at the log files on the server can tell you what version they are actually using.
Vault 2014 (RTM) 18.0.110.x
Vault 2013 (SP1) 126.96.36.199
Vault 2013 (RTM) 188.8.131.52
Vault 2012 (Update 2) 184.108.40.206
Vault 2012 (Update 1) 16.1.58
Vault 2012 (RTM) 16.0.56.X
Vault 2011 (Update 2) 15.2.66.X
Vault 2011 (Update 1) 15.1.58.X
Vault 2011 (RTM) 15.0.58.X
Vault 2010 (Update 2) 14.2.x.x
Vault 2010 (Update 1) 14.1.x.x
Vault 2010 (RTM) 14.0.63.x
Vault 2009 (RTM) 13.0.47.x
Vault 2008 (SP1) 12.1.145.x
Vault 2008 (RTM) 12.0.123.x
RTM = Release to Manufacturing, ie, no patches applied