[CentOS] Physically moving a mail server vs. cached DNS

Sat Jul 1 13:10:20 UTC 2017
Richard <lists-centos at listmail.innovate.net>

------------ Original Message ------------
> Date: Saturday, July 01, 2017 10:57:42 +0100
> From: Pete Biggs <pete at biggs.org.uk>
> Subject: Re: [CentOS] Physically moving a mail server vs. cached DNS
> On Sat, 2017-07-01 at 11:37 +0200, Nicolas Kovacs wrote:
>> Le 01/07/2017 à 11:00, Pete Biggs a écrit :
>> > That is controlled by the TTL (time to live) entry. A DNS server
>> > must refresh it's cache within the TTL for the entry. Using the
>> > '-a' option to host will give you more information:
>> So I would have to use the -a option with the old DNS server, to
>> know their TTL. 
> Yes, or use dig or something else that shows the TTL
>> I'm also wondering if some DNS server don't override the TTL
>> and keep the information longer. I remember such a case where the
>> DNS server of the french provider Orange kept a stale DNS
>> information forever.
> The TTL is part of the DNS record so no, they shouldn't override
> it, in the same way as they shouldn't override the A record or MX
> record. That doesn't mean that some providers don't do it "for
> operational reasons", but it's a stupid thing to do and will
> basically, literally, break the internet.
> P.

You should check to see if your old SOA is still showing themselves
as authoritative for your domain. If they are, then anyone who uses
their nameservers will still get the old record(s) for your domain.

If they are still showing themselves as authoritative (which I think
is the case) you will want to contact them to have them drop your
domain from their server(s), or at least get your host records
updated to point to your new servers.