Web Hosting Talk : Web Hosting Main Forums : Domain Names : why have more then one nameserver?

[Pete]

Why does everyone register ns1 and ns2 sometimes ns3 and ns4 all with different IPs???

isnt ns1.mydns.com enough?

(sorry if this sounds dumb, but it's a question :-)

[CobaltConn]

*Usually* ns1, and ns2 are two different servers.

Lets say you are on "ServerX"

If the server that ns1 is running on goes down, it proceeds to go to ns2, and if ns2 is on a different server...then ServerX can still load up...

[thewitt]

In a world with lots of computer systems, all using the same nameservers, you need to spread your nameservers around, so that you can always get to a nameserver, and then to one of your named computers.

In a world where there is one IP address associated with a domain, and www means the default level of your webserver docs directory, and you are hosting your nameservers, you may as well only have one nameserver - and in fast you may as well host it on the same computer as your website.

If your site is down, there is no reason to get to your nameserver.

In the case where your nameservers are serving hundreds or thousands of domains that are not on the same server, you want to be able to get to one of your nameservers at all times. This means they go on different networks, in different NOCs, in different countries, etc.

-t

[freakysid]

I have some domain where I am dns hosting the records on my own nameserver runnign on my box. I fall into the category thewitt described where if my box goes down then there is no point being able to reach my nameserver because the domains' web and mail servers will be down too.

However, it is still good (and compolsory anyway) to have two name servers with different IPs registered (even though they both point to the same physical nameserver). Say you need to change IP numbers or move the name server onto a different machine. You plan things out so that theoritically, you change the registered IP number of your primary name server over to your new address. While it is still propergating through the internet, if people can't reach your primary name server, your secondary name server will still be pointing to your current - soon to be ex-name server. Then after a few days, you move your nameserver onto the new machine and people will be able to find your new primary name server under the new IP and the secondary nameserver stops being reachable at the old IP, but now you update the registered number of your secondary ip anyway. So, hopefully, you will have made a graceful transition onto your new machine and ip numbers (well in theory anyway).

[terrastudios]

even if you host on the same box as your dns server, it is best to have at least two name servers, consider the following:

BIND (or whatever server you use) fails :O
Apache/Sendmail/Proftpd.. etc... continues to run

With only one nameserver, regardless of the fact that Apache etc.. is running, your domain is down.

But as you have a second name server, hosted on a different box, even if Bind fails on the first box, at least your domains stay up.

Regards,

Matt Brocklehurst,
Terrastudios.co.uk