What version of SEP 12 can we install on Windows Server 2012 Enterprise Server?

SEP 12.1 RU2 is the first release to support 2012 so if youre on that or higher than yes.

See here which is also for 2012:

About Windows 8 and Symantec Endpoint Protection 12.1

http://www.symantec.com/docs/TECH174348

Hi

Please install SEP 12.1.3 on Windows Server 2012

Regards

Hi,

Please check with below threads.

Installation of SEP 12.1.3 on Server 2012

https://www-secure.symantec.com/connect/forums/installation-sep-1213-server-2012

http://www.symantec.com/business/support/index?page=content&id=TECH174673

Hello,

Symantec Endpoint Protection 12.1 RU2 and later are supported on Windows 8 and Windows Server 2012.

All flavours of Windows Server 2012 are supported from SEP 12.1 RU2 onwards.

System Requirements for Symantec Endpoint Protection, Enterprise and Small Business Editions, and Network Access Control 12.1.2 and 12.1.3

http://www.symantec.com/docs/TECH195325

For information on how to obtain the latest build of Symantec Endpoint Protection, read How to obtain an update or an upgrade for your Symantec corporate product.

Check this Article:

About Windows 8 and Symantec Endpoint Protection 12.1

http://www.symantec.com/docs/TECH174348

Just on a kind note: Symantec Endpoint Protection 12.1 RU3 has released and check this BLOG's:

What's new with Latest Symantec Endpoint Protection SEP 12.1.RU3

Latest Symantec Endpoint Protection Released - SEP 12.1.RU3

Hope that helps!!