The TTL has been set to 1H, so that IP changes for example.com can be made more quickly.

The registrar has been configured with ns1.example.com and ns2.example.com, verified using WHOIS lookup. ns1 and ns2 are based in Texas.

We're moving all of our stuff to New Jersey, because the new owner thinks it's a good idea.

So, we routed A records example.com, www.example.com, etc to New Jersey now, and that leaves ns1 and ns2 which are still based in Texas.

So, we set up new nameservers in New Jersey ns3.example.com, and ns4.example.com, and they are working well, but at this point the registrar/WHOIS is still set up to direct users to continue using ns1 and ns2.

I've been told that a 48-hour update is required for the WHOIS nameserver updates to take effect, so the logical course is to list the New Jersey DNS servers (ns3.example.com and ns4.example.com) on the WHOIS, then wait at least 48 hours before shutting down the Texas servers (ns1.example.com and ns2.example.com).

But, since the TTL is set to 1H, do I still need to wait 48 hours? Will public/recursive/ISP DNS servers cache the Registar/WHOIS nameserver list for longer than the TTL of the A records?

(I am not concerned about systems that ignore the TTL entirely, I'm only asking whether those that respect A record TTL will also use that same TTL for the Registar/WHOIS nameserver list)

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    WHOIS is informational. It has no bearing on the discovery of your name servers or DNS resolution of your domain. What matters is what name servers are listed as name servers at the domain Registrar for your domain as it is the Registrar's responsibility to update the parent servers of your name server change. Have you added NS3 and NS4 as name servers at the domain Registrar? – joeqwerty Feb 27 '14 at 15:30
  • In this scenario, yes. Logged in to the registrar, replaced NS1 & NS2 with NS3 and NS4. I used the WHOIS to verify the new information was successfully registered, but if you can recommend a dig command, I can use that instead. – Bryan Field Feb 27 '14 at 23:44
  • What I'm saying is that the WHOIS information is informational and has no bearing on actually finding the name servers for your domain. Use NSLOOKUP or DIG to query the parent servers for your name servers. The parent servers will be the .com, .net, etc. servers for your domain TLD (.com, .net, etc.). – joeqwerty Feb 27 '14 at 23:47

You have to ask your registrar this question. Sometimes you can directly control your NS records and their TTLs, sometimes your registrar will have their own settings.

  • Fortunately, I found out today, I don't have to play out this scenario. – Bryan Field Feb 28 '14 at 19:15

Not everyone respects TTL and set their own timeouts for their caches. The 48 hours which is often quoted, will in most cases be more than sufficient but in some cases even that won't be long enough.

  • I've noticed some systems seemingly never look for updated DNS, certainly they memorize the A records for longer than the TTL, regardless of whether the nameservers changed. I am not worried about those. – Bryan Field Feb 27 '14 at 23:46
  • My question is, for a DNS server that noticed the TTL expired, and decides to look up the new A record, will DNS servers generally also look up the nameservers, or will they use cached nameservers to look up new A records? – Bryan Field Feb 27 '14 at 23:47

A nameserver's TTL is defined in its SOA record (serial, refresh, retry, expire, minimum ttl). Refresh, retry, expire all determine how a secondary nameserver (not the rest of the internet) behaves WRT checking for zone refresh, how often to retry on failure, and when to decide that everything it knows is stale. Min TTL is for all records in the zone that don't have explicitly set TTLs.

If your registrar says 48 hours, let it take 48 hours.

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