Hello, i have a question relating to DNS servers, in the past when people have looked to me to buy hosting off of many of them have asked what the address of my DNS servers are because they all seem to think that all registrars require DNS servers of the site host to function, i have asked a friend of mine the same question but he is unsure, my question is when setting up multiple DNS servers do they require separate Public IPs or can they have the same public IP but different private IP, my friend says they need separate public IP address' but he also isnt 100% sure

Hi mike,
if you look into RFC2182 and RFC1035 you should get the answer. I went to DNSStuff.com quite a bit when I was trying to learn about DNS. It's an excellent resource.
Good luck.
Joe

As Joe mentioned, the RFCs hold all the answers on DNS, and they're a good resource. I'm also really fond of the book "DNS and BIND" by Cricket Liu and Paul Albitz, published by O'Reilly. It's perhaps the best-written of several really good O'Reilly books on system administration (it's also really popular, so your local library probably has a copy).

But, to answer this specific question:

Yes. You need two nameserver "glue" records, each with its own IP. This is strictly enforced by all registrars.

The theory behind this rule is that without DNS all services fail no matter what else you do. So, backup mail servers cannot work (likewise for all other services...but SMTP has built-in reliability mechanisms). In reality, for many of us that run everything on one box (mail, web, databases, etc.) if our primary box fails, DNS doesn't matter anymore.

I do recommend for any serious business server that you have a real backup DNS server that also acts as your holder and forward MX server. Both of these bits are easy to setup and are documented over on the documentation page. You can get a virtual dedicated server for less than $50/month just for this purpose.

Joyent has "Accelerators" which are Solaris Zones...and they already have Virtualmin GPL installed and pre-configured on them, so they can pretty much handle both of those tasks out of the box. I would say EC2 is another way to get cheap "dedicated" service, but it has proven pretty unreliable during the beta period...give it a little time to stabilize and it'll be nice. Jamie built a Virtualmin GPL pre-installed image for EC2 a while back, and I plan to build a couple of new ones with CentOS 5 and Debian 4 in the not distant future (once the new installer for GPL on those platforms is released).

allright thanks for the explanation, when i get the funds to do so i will setup a dedicated DNS server under another IP address, most likely under my parents internet :P im sure if i explain it long enough to them they will allow it

I should have mentioned that you can fake it with a single server. You just need an extra IP address. If you only have one server for all of your services, anyway, there is no benefit to having a "real" secondary DNS server. But the registrar still requires you to pretend that you do. ;-)