On Wed, Mar 07, 2001 at 09:40:30AM -0800, Greg White wrote:
[snip]
>
> I may have to take back what I said about the MX records -- I cannot get
> any ns for mail.ru to tell me anything but mx.port.ru for the MX record
> for mail.ru. It appears they're trying to load-balance based on
> round-robin DNS (which strikes me as silly for MX records in most cases)
> with a large (for round-robin -- 12H) TTL. That kinda defeats the
> purpose of round-robin, no? So mx.port.ru is broken (IMHO) in more than
> one way....
No, this kind of round-robin DNS isn't TTL-based. It does, however,
rely on sending MTAs to try A records randomly or sequentially.
All our MXes (for about 60.000 domains) used to be
example.com MX 3 inbound.vuurwerk.nl
example.com MX 7 fallback.vuurwerk.nl
where inbound.vuurwerk.nl has 2 A records. The first server mentioned
in the zonefile would get *way* more mail than the other.
We now changed this to
example.com MX 12800 in1.mail.vuurwerk.net
example.com MX 12800 in2.mail.vuurwerk.net
example.com MX 12816 fallback.vuurwerk.nl
the load seems to be spread more evenly now. (altho we got rid of a
couple of looping messages on the overloaded server as well, so we
have no real evidence).
[yes, I know in-bailiwick MXes are better but I'm not adminning the
DNS and it's all scripted. Will fix that :)]
> If the OP's MX record information was correct, my advice would have
> been correct. Given what I see now, for at _least_ twelve hours, qmail
> will keep trying the IP address that the local resolver has in its cache
> for mx.port.ru, and the only way to get mail to deliver to this domain
> would be (and feel free to correct me on this) to flush the cache of the
> local resolver and hope that it caches a different A record.
Uh, no. The local resolver will have all IPs in it's cache. dnscache
however returns them in the same *order*. Most applications only use
the first IP in the list they get back. I don't know what qmail does.
Greetz, Peter.
