[dns-operations] How to plan dns server IP change?

[Paul Vixie]

Simon Munton wrote:
> On 15/06/2014 18:18, Mohamed Lrhazi wrote:
>> Also, been thinking that since we cant have both old and new IPs up at
>> the same time,
>
> Unless this is a restriction imposed by your registrar, it is fine to
> have multiple IP Addresses for one name server.

not exactly.

> We ran tests on this and found multiple IP Addresses share the load as
> much as multiple NS records. As far as traffic was concerned there
> seemed to be no difference between these two choices.
>
> So two NS records with two IPv4 addresses each will share the load
> ~25% to each IP.

in terms of load sharing when all addresses are answering normally, this
is true.

> If one IP stops responding resolvers should just favour the ones that
> are still working, so that's what I'd use to migrate the IP over.

when one of several A/AAAA RR's attached to an NS responds with SERVFAIL
or REFUSED, the others are also presumed broken, and the next NS is
tried. thus, having an old and new address both attached to the same NS
during a transition will only work well if you can ensure that both old
and new addresses continue to work during the transition.

vixie