reverse lookup returning "localhost"

[Andrew Garnett]

All,
I'm a bit baffled - we have an internal top-level DNS server for "company.com" (bind 9.2.1) which is reverse-resolving all IP addresses beginning with 207.x.x.x to "localhost".
We have internal reverse lookup zones which work fine, and valid external reverse lookups seem to work fine. I don't have any references to 207 at all (and if we did, they wouldn't resolve every address to "localhost"). 
Both nslookup and dig seem to suggest that it's getting this response locally, but I don't run a 207 zone. Sorry if I am missing something obvious. What can be returning "localhost" ?

Here's the dig info (run on the actual DNS server 10.56.11.55) :-

dig @10.56.11.55 -x 207.1.2.3
; <<>> DiG 9.2.0 <<>> @10.56.11.55 -x 207.1.2.3
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19725
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1
;; QUESTION SECTION:
;3.2.1.207.in-addr.arpa.                IN      PTR
;; ANSWER SECTION:
3.2.1.207.in-addr.arpa. 172800  IN      PTR     localhost.
;; AUTHORITY SECTION:
207.in-addr.arpa.       172800  IN      NS      localhost.
;; ADDITIONAL SECTION:
localhost.              82574   IN      A       127.0.0.1
;; Query time: 1161 msec
;; SERVER: 10.56.11.55#53(10.56.11.55)
;; WHEN: Thu Apr 12 12:55:05 2007
;; MSG SIZE  rcvd: 93

Thanks for any help,
A


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