[Gllug] [: qmail, dhcp, dns query]

[Ian Northeast]

bradut at intelesuri.net wrote:
>>What exactly was it looking up? There are some combinations of records 
>>(e.g. MX -> CNAME) which are illegal but some nameservers tolerate. Also 
>>some nameservers may baulk at long chains of CNAMEs, which are legal but 
>>discouraged. Or if you don't know what it was looking up, where were you 
>>trying to send mail to? If it was to this group I can't explain it as 
>>linux.co.uk has 2 MXs both of which point to As which is totally correct 
>>as would be expected.
> 
> 
> I was sending test messages to myself on freeuk.com, hotmail.com

No CNAMEs involved in sending mail to either of them. They both have 
regular MX->As. In Hotmail's case, rather a lot of them (dig hotmail.com 
mx returns 4 answers and 18 "additional"s), but there's nothing wrong 
with that.

Do you have the exact error message Qmail issued? It could be informative.

>>The nameserver in the router is likely to be very simplistic. The ones 
>>you have replaced it with are probably more sophisticated. So it is 
>>possible that you have hit a combination which is either illegal but 
>>tolerated by the nameservers you are now using, or too much for your 
>>router's nameserver to cope with.
> 
> the namesevers on the router are exactly the same as in my
> /etc/resolv.conf those provided by my isp, eclipse.net.uk That's why I
> couldn't understand why there weren't picked up by qmail when it had the
> router as its nameserver, from which to pick up the isp's nameservers...
> anyway that's the way I imagine it to work...

Not quite. The router contains a nameserver. Not a very complex one.

The nameserver in the router probably does no more than forward all 
queries to the ISP ones it picked up from DHCP. As such it *ought* to 
work perfectly as it doesn't really do anything. But your experience 
indicates otherwise.

Your Linux box has no idea what nameservers the router is using. All it 
knows with the default configuration is that the router is the 
nameserver. It neither knows nor cares how the router resolves the queries.

Regards, Ian


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