What is a Round Robin DNS? and other security issues..

[Jari Ivanoff]

Sorry for this perhaps trivial question.. but what is a Round Robin DNS??

And some other questions... is there some one that could tell me what
security issues i should think about when i set up a DNS?
I am running Bind 8.2.x on a RedHat 6.1 for our internal network at my job.
and we are considering our own Internet connection, with a NT based Guardian
Firewall to the outside. I have thought about a DNS server on the DMZ and
one on the inside, with a secondary external DNS at one of the "sister"
corporations sites, which i am helping to administer anyway ( both companies
are have their external connections in our serverroom but with their own
links and firewalls).
What should i think about to get the most secure setup for us?
/Jari Ivanoff