I have a single forest / single domain at 2008 r2 functional levels.

All DCs have been upgraded to 2012 r2.

We do however have some 2000 member servers in the domain.  Will these servers have issues after the forest and domain lift?

Hi,

Thanks for your post.

 New features that rely on the Functional Level are generally limited to Active Directory itself. For example, objects may replicate in a new and different way, aiding in the efficiency of replication or increasing the capabilities of the DCs. There are exceptions that have nothing to do with Active Directory, such as allowing NTFRS replacement by DFSR to replicate SYSVOL, but there is a dependency on the version of the operating system. Regardless, changing the Domain or Forest Functional Level should have no impact on an application that depends on Active Directory.

Please read the articles for more details

What is the Impact of Upgrading the Domain or Forest Functional Level?

http://blogs.technet.com/b/askds/archive/2011/06/14/what-is-the-impact-of-upgrading-the-domain-or-forest-functional-level.aspx

Best Regards,

Mary Dong

Hi,

As per the information provided in the below thread, there will be no problem on windows 2000 members servers, but it is recommended to replace the windows 2000 servers.

Checkout below thread on similar discussion,
https://social.technet.microsoft.com/Forums/windowsserver/en-US/a6070b2f-827c-4337-81ac-ffa0a1a08bf0/windows-2012-dcs-and-windows-2000-member-servers?forum=winse