Re: Eric Sunshine mail delivery failure

[Eric Sunshine <sunshine@sunshineco.com>]

On Sun, Aug 23, 2015 at 2:48 PM, Eric Sunshine <sunshine@sunshineco.com> wrote:
> On Sun, Aug 23, 2015 at 2:36 PM, Elia Pinto <gitter.spiros@gmail.com> wrote:
>> Il 23/Ago/2015 20:26, "Eric Sunshine" <sunshine@sunshineco.com> ha scritto:
>>> I did change the CNAME to an A just in case, though who knows how long
>>> it will take for the change to propagate over to web.de's server.
>> Anyone can check Here https://dnschecker.org/#CNAME/Mail.sunshineco.com
>> It would fail with your change
>
> Interesting service; thanks for the pointer. However, since it's just
> querying a random set of DNS servers, it's not necessarily indicative
> of whether the change has actually propagated to the DNS server(s)
> answering web.de's mail server's queries. Local configuration (TTL's,
> etc.) on those servers or anywhere in between, as well as network
> conditions, could impact propagation to an unknown degree.

Also, the propagation time of the A record can be quite different from
the point at which the CNAME record finally expires (based upon its
TTL, which may differ dramatically from server to server), so the
above CNAME query may continue to succeed long after the A record has
propagated.