BIND-9.7.0 noanswer_response sideways referral
Mark Andrews
marka at isc.org
Fri Apr 23 06:44:53 UTC 2010
In message <394305900.760891271963571419.JavaMail.root at sz0093a.westchester.pa.m
ail.comcast.net>, Lou Picciano writes:
> Bind Users:
>
> Wonder if anyone has seen this, and can offer an insight?
BIND 9.7.0 does a better job of detecting anonmallies in responses
to iterative queries. You were just lucky that the responses were
accepted by the previous versions. The answer was non-authoritive
(no "aa" in flags) and recursion was not requested (no "rd" in flags).
This would not normally happen unless there is something mucking with
the query / response.
> 22-Apr-2010 12:06:52.083 resolver: debug 10: received packet:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60591
> ;; flags: qr ra ; QUESTION: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags: do; udp: 4000
> ;; QUESTION SECTION:
> ;ibm.com. IN A
>
> ;; ANSWER SECTION:
> ibm.com. 21578 IN A 129.42.17.103
> ibm.com. 21578 IN A 129.42.18.103
> ibm.com. 21578 IN A 129.42.16.103
IBM's servers respond like this. Note "aa" is set and "ra" is not set.
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17828
;; flags: qr aa; QUERY: 1, ANSWER: 3, AUTHORITY: 4, ADDITIONAL: 6
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;ibm.com. IN A
;; ANSWER SECTION:
ibm.com. 21600 IN A 129.42.18.103
ibm.com. 21600 IN A 129.42.16.103
ibm.com. 21600 IN A 129.42.17.103
;; AUTHORITY SECTION:
ibm.com. 3600 IN NS ns.austin.ibm.com.
ibm.com. 3600 IN NS internet-server.zurich.ibm.com.
ibm.com. 3600 IN NS ns.watson.ibm.com.
ibm.com. 3600 IN NS ns.almaden.ibm.com.
;; ADDITIONAL SECTION:
ns.austin.ibm.com. 86400 IN A 192.35.232.34
ns.watson.ibm.com. 3600 IN A 129.34.20.80
ns.almaden.ibm.com. 86400 IN A 198.4.83.35
internet-server.zurich.ibm.com. 1800 IN A 195.176.20.204
internet-server.zurich.ibm.com. 1800 IN AAAA 2001:620:20:fe01:100::2000
;; Query time: 358 msec
;; SERVER: 129.34.20.80#53(129.34.20.80)
;; WHEN: Fri Apr 23 16:42:33 2010
;; MSG SIZE rcvd: 286
Mark
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
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