Re: [squid-users] Very strange DNS problem

On 08/23/2013 05:04 AM, Amos Jeffries wrote:
> On 23/08/2013 4:43 a.m., johnh_at_primebuchholz.com wrote:
>> Greetings List,
>>
>> This is a really strange problem, that I can't tell if it's squid or
>> bind
>> causing it. Here's the summary:
>>
>> For only ONE address, whenever I attempt to access it through the proxy,
>> the record disappears from DNS, and the retry time changes too.
>> Essentially, accessing www.thisdomain.com works, but a link to a
>> portal on
>> that page to the subdomain login.thisdomain.com causes the problem.
>> Here's
>> a the output of dig from before accessing the page:
>>
>> ; <<>> DiG 9.4.1-P1 <<>> login.thisdomain.com
>> ;; global options: printcmd
>> ;; Got answer:
>> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 45037
>> ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0
>>
>> ;; QUESTION SECTION:
>> ;login.thisdomain.com. IN A
>>
>> ;; ANSWER SECTION:
>> login.thisdomain.com. 17 IN A 111.222.333.123
>>
>> ;; AUTHORITY SECTION:
>> thisdomain.com. 168319 IN NS ns1.thisdomain.com.
>> thisdomain.com. 168319 IN NS ns2.thisdomain.com.
>>
>> ;; Query time: 0 msec
>> ;; SERVER: 127.0.0.1#53(127.0.0.1)
>> ;; WHEN: Thu Aug 22 12:29:57 2013
>> ;; MSG SIZE rcvd: 88
>>
>> You can do anything to request the address from bind and it works,
>> *except* try to access it through squid. Bypassing squid and going
>> directly through the firewall works fine.
>>
>> Now, immediately after you try to access it through squid:
>>
>> ; <<>> DiG 9.4.1-P1 <<>> login.thisdomain.com
>> ;; global options: printcmd
>> ;; Got answer:
>> ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 43943
>> ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
>>
>> ;; QUESTION SECTION:
>> ;login.thisdomain.com. IN A
>>
>> ;; AUTHORITY SECTION:
>> thisdomain.com. 298 IN SOA ns1.thisdomain.com.
>> serv.anotherdomain.com. 2006062510 3600 3600 2592000 300
>>
>> ;; Query time: 0 msec
>> ;; SERVER: 127.0.0.1#53(127.0.0.1)
>> ;; WHEN: Thu Aug 22 12:30:06 2013
>> ;; MSG SIZE rcvd: 95
>>
>> After the 5-minute retry shown above expires, the original record
>> reappears.
>>
>> Ideas? Should I be looking at squid, or bind for the issue? Has anyone
>> seen anything similar before? All other proxy and dns operations work
>> perfectly, and it's a pretty heavily utilized proxy. I'm stumped.
>
> Keep in mind that Squid is no just performing a standard A record
> lookup. It is performing both AAAA and A record lookups with EDNS
> advertisement on each.
>
> I've seen similar issues when testing the EDNS extensions and >16KB
> jumbogram packets through a consumer retail ADSL device. The EDNS
> extension on A record would crash the devices DNS relay or something
> to that effect.
>
> I've also heard about some older versions of bind having strange
> issues when AAAA record lookups were combined with certain SERVFAIL
> responses from upstream. If you have anything less than bind 9, please
> upgrade.
>
> Amos

Thanks Amos. I'll give upgrading a try - I'm on bind 9, but I'll
upgrade to a newer release and see how that goes.

-John

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