[squid-users] Very strange DNS problem

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.

-John

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