Mailing List Archive: comcast.net and CNAME_lookup_failed

comcast.net and CNAME_lookup_failed_temporarily

Aug 24, 2012, 1:22 PM

Post #1 of 4 (2533 views)

hello all, i'm receiving CNAME_lookup_failed_temporarily on on
particular qmail server for emails being sent to comcast.net addresses.
it's the only domain that is having this issue yet i can send mail to
comcast just fine from many other systems. has anyone seen or heard of
similar issues with comcast? can it possibly be something in the qmail
code?

my setup is a basic lifewithqmail install

k

Re: comcast.net and CNAME_lookup_failed_temporarily [ In reply to ]

nicolai-qmail at chocolatine

Aug 24, 2012, 1:30 PM

Post #2 of 4 (2463 views)

Permalink

On Fri, Aug 24, 2012 at 01:22:15PM -0700, Kirk Rogers wrote:
> hello all, i'm receiving CNAME_lookup_failed_temporarily on on
> particular qmail server for emails being sent to comcast.net addresses.

Look at the last bit of

http://cr.yp.to/qmail/faq/outgoing.html

Nicolai

Re: comcast.net and CNAME_lookup_failed_temporarily [ In reply to ]

amb-sendok-1348434799.icnnmflnenohkkajcang at bradfo

Aug 24, 2012, 2:13 PM

Post #3 of 4 (2446 views)

Permalink

Thus said Kirk Rogers on Fri, 24 Aug 2012 13:22:15 PDT:

> hello all, i'm receiving CNAME_lookup_failed_temporarily on on
> particular qmail server for emails being sent to comcast.net
> addresses.

comcast is publishing a huge response to an ANY DNS query:

$ dnsq any comcast.net dns102.comcast.net | head -3
255 comcast.net:
2840 bytes, 1+24+5+14 records, response, authoritative, noerror
query: 255 comcast.net

That's 2840 bytes of DNS data.

In this particular case, running dnscache on your server might alleviate
the problem. I have never had to patch qmail for CNAME lookup failure
issues, however, your situation might be different. I sent an email to
postmaster@comcast.net and it was accepted, so my qmail had no problems
looking up the domain. My qmail does not have any patches applied for
CNAME lookup problems.

qmail uses an ANY query to lookup the DNS information for the recipient
domain. This is historical behavior (due to some bugs in other MTAs)
that is apparently no longer required:

http://marc.info/?l=qmail&m=134062672511072&w=2

Andy

Re: comcast.net and CNAME_lookup_failed_temporarily [ In reply to ]

kirk at icapsolutions

Aug 24, 2012, 3:16 PM

Post #4 of 4 (2439 views)

Permalink

i applied the patch ... all is well.

thx andy,
k

On 8/24/2012 2:13 PM, Andy Bradford wrote:
> Thus said Kirk Rogers on Fri, 24 Aug 2012 13:22:15 PDT:
>
>> hello all, i'm receiving CNAME_lookup_failed_temporarily on on
>> particular qmail server for emails being sent to comcast.net
>> addresses.
> comcast is publishing a huge response to an ANY DNS query:
>
> $ dnsq any comcast.net dns102.comcast.net | head -3
> 255 comcast.net:
> 2840 bytes, 1+24+5+14 records, response, authoritative, noerror
> query: 255 comcast.net
>
> That's 2840 bytes of DNS data.
>
> In this particular case, running dnscache on your server might alleviate
> the problem. I have never had to patch qmail for CNAME lookup failure
> issues, however, your situation might be different. I sent an email to
> postmaster@comcast.net and it was accepted, so my qmail had no problems
> looking up the domain. My qmail does not have any patches applied for
> CNAME lookup problems.
>
> qmail uses an ANY query to lookup the DNS information for the recipient
> domain. This is historical behavior (due to some bugs in other MTAs)
> that is apparently no longer required:
>
> http://marc.info/?l=qmail&m=134062672511072&w=2
>
> Andy