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

[Pete Biggs]

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.