To be up to date you should go for the MCSA: Windows Server 2012
There is an upgrade path that you could follow.
- Exams 70-648 and 70-646 to upgrade to the MCSA: Windows Server 2008.
- Then Exam 70-417 to upgrade from 2008 to MCSA: Windows Server 2012.
But I think it is better to leap over the Windows Server 2008 and just do the three basic exams required for the MCSA: Windows Server 2012.
70-410 Installing and Configuring Windows Server 2012
70-411 Administering Windows Server 2012
70-412 Configuring Advanced Windows Server 2012 Services
Same number of exams but without the issue when studying of confusion over what was introduced with Server 2008 or with Server 2012.