Best Practices for DNS order on domain controllers

Hello,

I would like an answer about the configuration of DNS on the domain controllers.

I suppose the correct configuration is the following :
Primary DNS : another DNS
Secondary DNS : 127.0.0.1

I am aware it could be exist a island phenomene on Windows 2k3 but with 2008R2/2012/2012R2, it still exist ?

What the consequence of a bad configuration (latency to startup ? etc ?)

Thanks