Rackspace has corroborated our findings with the va.gov DNS misconfiguration (their response pasted below). Which brings me back to my question: is there a way to make qmail more resilient to these kind of DNS issues?
Quinn ----- Forwarded message from [email protected], 21 Jul 2013 07:46:23 ----- Greetings Quinn, From my investigation, this seems to be an issue with IPv6 contained in the DNS record and the va.gov nameservers themself. From your server and all other machines I've tested on, I can get the IPv6 AAAA records: [root@oak ~]# lsmod|grep ipv6 ipv6 437985 38 cnic,ib_sdp,ib_ipoib,rdma_cm,ib_addr xfrm_nalgo 43333 1 ipv6 [root@oak ~]# dig va.gov AAAA ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-20.P1.el5_8.6 <<>> va.gov AAAA ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 8335 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;va.gov. IN AAAA ;; ANSWER SECTION: va.gov. 60 IN AAAA 2610:d8:1000:28::28:221 ;; Query time: 6 msec ;; SERVER: 72.3.128.240#53(72.3.128.240) ;; WHEN: Sun Jul 21 23:40:21 2013 ;; MSG SIZE rcvd: 52 Which precludes there being any DNS connectivity issues on our network. It seems the DNS response from the nameservers are inconsistent even for external services querying the DNS; you can check by using the following: http://pingability.com/zoneinfo.jsp?domain=va.gov http://leafdns.com/index.cgi?testid=B91E5367 Notice that the glue records for MX are mismatched and/or missing, which would indicate a reason for SMTP/mail issues and the va.gov domain. So the problem essentially lies with the DNS zone for va.gov and any one of the 4 nameservers not answering correctly under varying requester conditions. I will leave this ticket should you have any further insight on the issue. If you have additional questions or require further support, please don't hesitate to ask! Best regards, Chris N. Linux Administrator Rackspace Managed Support // US (800) 961-4454 --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
