DNS Configuration for routers

Hi
I am novice to world of routers.
I have a question :

On a router If I want to use DNS can I use one loop back address and
respective hostnames in DNS or we need to configure for all IP
addresses?

Here loop back address is in context of a Router. Usually every router
has one Loop Back address and many IP addresses for various interfaces.
Should we add all the addresses in to DNS data file , when we start
using DNS ? Or just the loop back address is
sufficient.

Experts pls answer ASAP.

Thanks in advance
Karuna