Re: CNAME Lookup failure for MX microsoft.com

Hi,

I did a little investigation, and it turned out to be the 'oversized' UDP 
packet problem.

Obviously, at least one of the queried NS sends oversized packets.

Changing udpbuf to 4096 in dns_transmit.c solves (or at least relaxes) the 
problem.

Comments ?

regards.
--eh.


--On 3. Februar 2009 09:19:03 +0100 Erwin Hoffmann <[email protected]> wrote:

> Hi,
>
> since a while Qmail gave be an error, trying to send email to
> microsoft.com (CNAME lookup failure) and bouncing the mail.
>
> After some investigations yesterday, I got some interesting insights
> regarding microsoft.com:
>
> dnsmx microsoft.com
> 10 mail.global.frontbridge.com
> dnsname mail.global.frontbridge.com
> dnsname: fatal: unable to parse IP address mail.global.frontbridge.com
>
>
> And looking at the dnscache log:
>
>
> @40000000498755a826eba174 tx 0 MX microsoft.com. microsoft.com.
> 207.68.160.190 207.46.66.126 65.55.238.126 213.199.161.77 65.54.240.126
> @40000000498755a8326c1e84 rr 207.68.160.190 003600 MX  microsoft.com. 10
> mail.global.frontbridge.com.
>
> A little later:
>
> dnsname 207.68.160.190
> ns1.msft.net
>
>
> dnsq mx microsoft.com 207.46.66.126
> 15 microsoft.com:
> 71 bytes, 1+1+0+0 records, response, authoritative, noerror
> query: 15 microsoft.com
> answer: microsoft.com 3600 MX 10 mail.global.frontbridge.com
>
> And again later:
>
> dnsip mail.global.frontbridge.com
> 216.32.181.22
>
> @400000004987577e1586d764 tx 0 A mail.global.frontbridge.com. com.
> 192.42.93.30 192.41.162.30 192.55.83.30 192.26.92.30 192.31.80.30
> 192.43.172.30 192.5.6.30 192.12.94.30 192.54.112.30 192.52.178.30
> 192.48.79.30 192.35.51.30 192.33.14.30
> @400000004987577e1fe70f94 rr 192.42.93.30 172800 A ns18-f.bigfish.com.
> 207.46.51.85
> @400000004987577e1fe81934 rr 192.42.93.30 172800 A ns19-f.bigfish.com.
> 213.199.154.21
> @400000004987577e1fe8d4b4 rr 192.42.93.30 172800 A ns20-f.bigfish.com.
> 216.32.180.21
> @400000004987577e1fe99bec rr 192.42.93.30 172800 A ns21-f.bigfish.com.
> 216.32.181.21
> @400000004987577e1feb0b1c rr 192.42.93.30 172800 NS  frontbridge.com.
> ns18-f.bigfish.com.
> @400000004987577e1feb9f8c rr 192.42.93.30 172800 NS  frontbridge.com.
> ns19-f.bigfish.com.
> @400000004987577e1fec2c2c rr 192.42.93.30 172800 NS  frontbridge.com.
> ns20-f.bigfish.com.
> @400000004987577e1fecbcb4 rr 192.42.93.30 172800 NS  frontbridge.com.
> ns21-f.bigfish.com.
> @400000004987577e1fed4d3c stats 71 25958 1 0
> @400000004987577e1fee2fcc cached A ns18-f.bigfish.com.
> @400000004987577e1feecc0c cached A ns19-f.bigfish.com.
> @400000004987577e1fef607c cached A ns20-f.bigfish.com.
> @400000004987577e1feff4ec cached A ns21-f.bigfish.com.
> @400000004987577e1ff0c00c tx 0 A mail.global.frontbridge.com.
> frontbridge.com. 216.32.181.21 216.32.180.21 213.199.154.21 207.46.51.85
> @400000004987577e2bbd132c rr 216.32.181.21 000010 A
> mail.global.frontbridge.com. 216.32.181.22
> @400000004987577e2bbe18e4 stats 71 26013 1 0
> @400000004987577e2bbf5164 sent 71
>
>
> Obviously, I took dnscache too long to fetch the address.
>
> Q: Has anyone seen the same problem or perhaps can suggest a solution ?
>
> regards.
> --eh.
>
> Dr. Erwin Hoffmann | FEHCom | http://www.fehcom.de/
>