Microsoft has released a new activation methodology named Active Directory-based Activation (ADBA) that provides several benefits over the traditional KMS/MAK activation strategies. It uses a server role on a Server 2012 machine to activate clients and then stores activation information in Active Directory. This aspect of ADBA provides built-in protection against a single point of failure for licensing activation within an environment (provided there is more than one domain controller present). There are a couple of notable differences between ADBA and KMS, summarized below:
Pros
o Doesn’t require 25 activation requests before licensing first client
o GUI-based activation mechanism
o Stores activation objects within AD (so if the host is lost all activation information isn’t lost as well)
o Capable of managing an entire forest with multiple domains (KMS is domain-specific)
Cons
o Only works with Windows 8+ / Server 2012+ / Office 2013+ activation
o Requires Server 2012 schema level
ADBA can also be used in conjunction with KMS/MAK to allow firms to transition seamlessly between activation methods for older and newer clients. The entire setup for this technology is about as simple as configuring KMS in an environment, but as illustrated above offers some notable benefits that many administrators will find appealing.
Further reading:
https://technet.microsoft.com/en-us/library/hh831612.aspx