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I currently host a DNS server to make it easier to manage our company's subdomains (we're web-devs). However we need to change the IP address of one of the DNS servers as the DNS service has been migrated to a new server hosted with to a new provider.

I seem to recall it's not as simple as just changing the A record of the ns2.domain.com as it has to be "globally registered" with the root servers or something? I can see where I changed the DNS server's registration details in my Network Solutions account and presumably I need to change the A record at the same time.

Before I change the A record for the DNS server though, I would like to find out the answer to the following: What does the "nameserver registration" process actually do and how can I validate it has been done correctly (eg from command line queries or using online tools)?

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With some minor caveats, it actually is as easy as changing the record at your registrar. Here's a high-level overview of what needs to be done, in what order, and some things to looks out for:

First, make sure the new server is responding to queries and is getting updates as it should. Once you've done this, change your local records to reflect the new address of the new server. Starting at this point, you will need to make sure you keep all three servers in sync with any zone updates. Any divergence, especially if the new server doesn't get an update, could have negative consequences down the road.

Now, go change your NS registration with your registrar (e.g. Network Solutions, GoDaddy, etc). This will probably involve editing a "nameserver record" (that's GoDaddy terminology, which I know because I use them) - more commonly this is called a "glue record". Once this is done, you wait. It usually takes 24 hours for this to propagate fully. At this point, you will start seeing some queries hit the new server, but you must keep the old server online since some queries will also be hitting it.

Once the 24 hours period is over (that period may be different, consult your registrar for how long they make it), you should then wait for the TTL to expire on all your records. This is commonly a week, but is determined by the TTL definition in your zones.

After the TTL wait, you should be able to turn off your old server, since all new queries should be going to the new server (or the one that wasn't changed). If it were me, I would wait another TTL period before doing so, simply because I'm paranoid, but that's a personal choice, not a requirement.

You can validate what you're calling the "nameserver registration" process several ways - my preferred method is to issue a whois <domainname>, which spits out your nameservers of record (among other information). You should see two nameservers - if you see the one that's not changing and the old server, wait 12 - 24 hours before re-querying. If after the time specified by your registrar you don't see the change, you need to either redo the change or you need to talk to your registrar for help.

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Thanks John - but how can I validate that Network Solutions have done their bit with the registration side of things? Is there a query I can do to see the new IP referenced? –  NickG Dec 3 '13 at 9:03
    
You look in your Network Solutions account and make sure it pulls up the new IP for your new glue record. It's really much simpler than you're trying to make it. –  John Dec 3 '13 at 12:24
    
I take your point but I like to understand what the interface has actually done. I still don't understand that. Is it not possible to somehow see this "glue" record externally? Using nslookup or something? I just hate not understanding what I'm actually doing when I'm changing something... After all the interface mentions an "up to 72 hour delay" so how can I query when this change has actually gone through to the root servers (or wherever it's mysteriously going). :) –  NickG Dec 3 '13 at 13:18
    
The delay is not inside NEtwork Solutions, it is the delay in expiring lookups that occur ever day, every minute, when other networks look up and cache these records. You can see the records externally using nslookup or (my preference) dig, but you have to be careful to find the glue records and not your records. As far as what the interface has done - it's changed a record that you "own" in a zone you don't "control". Ultimately, it just edited a text file. –  John Dec 3 '13 at 13:22
    
Alternately: the change goes to the root servers immediately. The old information was cached by other servers, and there is a period of time before those caches time out. No you can't shorten that time period, you have no control over the time other DNS servers save their caches. –  John Dec 3 '13 at 13:23
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