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Is it possible to change name servers with no downtime

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FredDirks

Programmer
Apr 11, 2005
2
US
My domain registar is Network Solutions but I have my name servers pointed to the ISP which hosts my web servers. I attempted to change my name servers from my current ISP to Network Solutions. When I made the change, I added the A records at Network Solutions point to my web servers (e.g. Once the change was made and I tried to resolve any host name for my domain, the request did tr to resolve using the Network Solutions name servers (ns1.worldnic.com) but none of the host names resolved. I called Network Solutions and they said that it would take 24-36 hours to propogate. My question is, is this really a "propogation" problem or is the problem that Network Solutions has not properyly configured their name servers yet? It seems to me that a propogation problem would cause it to resolve against the old name servers vs. not resolve at all? Am I missing something?
 
Thanks for your reply. Unfortunately, I can't wait 24-36 hours because there is already a live business website/email on this domain which becomes inaccessible while the addresses are unresolveable.
 
At your registrar, leave the name servers pointing to the old working ones for 24-36 hours, do an nslookup on your domain name at the new servers at that time, ensure they resolve correctly, and then switch it at your registrar. Don't delete your DNS record on the old name servers to allow for the rest of the world to propogate the new DNS server values.
 
The way to do this is to have the TTL's lowered a few days before the move.

1. On the ISP DNS servers, lower the TTL for the domain to say 900.

2. When Network Solutions create the zone file on thier servers using the incumbant data, ask them to keep the TTLs to a low value.

3. Migrating DNS servers then involves no downtime because both sets of DNS servers have the same values/zone data so the transfer is transparent, but only if planned correctly. The same hosts can be resolved from EITHER sets of DNS servers.

4. If changing the with a TTL of say 900 then propogation only takes 15 minutes and not 24-36 hours.

5. Once everything has been changed and propogated, set the TTL's back to normal values (eg 86400).

6. Once the domain has propogated then the ISP can remove the old zone files from their servers.

This way DNS server changes and zone data changes can be done with very little downtime.

If you understand how DNS is resolved and how records are cached then this can be done with very little downtime. However, what most people do is simply change the DNS servers and then make changes to the zone file and expect it to propagate and don't take into account the high TTL's on the incumbant data. The reason that you have this wait is because you don't have low TTL's and you aren't running the same zone data on both sets of DNS servers.

Chris.

**********************
Chris A.C, CCNA, CCSA
**********************
 
Network Solutions, or any registra for that matter, does not allow TTL changes from the default 86400. This is to protect themselves from system overload with millions of records to process.
 
The delegation data TTL can not be reduced so propagation of a name server change takes time but the actual zone TTL can be, which in this case is hosted with his current ISP.

If the new name servers are set up to accept queries for his domain and the 'zone' has a low TTL then the change over can be transparent. It doesn't matter which DNS servers are answering the queries during the NS change as long as they answer with the correct zone data and with low TTL's so that when the user wants to change records within that zone, propagation can be done quickly.

We do name domain/server changes every week and yes, our registrar is Network Solutions and we always lower TTL's for planned changes such as this. If planned correctly there is no need for any downtime. In the case of the op, his wasn't working because he tried to create the the new name servers ONLY and not on both sets that would still answer queries during the propagation period. If this had been planned better it could have been avoided.

Chris.

**********************
Chris A.C, CCNA, CCSA
**********************
 
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