odbc.ucas.com lookup problem

[Tony Finch]

On Tue, 20 Jul 2010, Chris Thompson wrote:
>
> However, I haven't yet been able to work out exactly *what* is wrong
> with the response, as demonstrated by dig (say). Any ideas?

Got it. The nameservers for ucas.com give a referral for odbc.ucas.com.
That means the zone for odbc.ucas.com is odbc.ucas.com. However the
nameservers for odbc.ucas.com give ucas.com as the SOA in their negative
replies. When BIND is checking the format of a NODATA response, it ignores
SOA and NS RR sets in the authority section that are not subdomains of the
query's zone. The result is it gets a negative response in a format that
doesn't match the cases in RFC 2308. The "invalid response" log message is
specific to format errors in negative responses.

; <<>> DiG 9.7.1-P2 <<>> aaaa odbc.ucas.com. @ns0.netcentral.co.uk.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21064
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 4
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;odbc.ucas.com.                 IN      AAAA

;; AUTHORITY SECTION:
odbc.ucas.com.          3600    IN      NS      ns-lp.ucas.com.

;; ADDITIONAL SECTION:
ns-lp.ucas.com.         3600    IN      A       195.188.99.250
ns-lp.ucas.com.         3600    IN      A       62.189.0.250
ns-lp.ucas.com.         3600    IN      A       81.171.139.250
ns-lp.ucas.com.         3600    IN      A       194.80.160.250

;; Query time: 12 msec
;; SERVER: 212.57.232.5#53(212.57.232.5)
;; WHEN: Tue Jul 20 18:24:06 2010
;; MSG SIZE  rcvd: 115


; <<>> DiG 9.7.1-P2 <<>> aaaa odbc.ucas.com. @ns-lp.ucas.com.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 30540
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;odbc.ucas.com.                 IN      AAAA

;; AUTHORITY SECTION:
ucas.com.               86400   IN      SOA     ucas.com. administrator.ucas.com. 998545544 28800 7200 604800 86400

;; Query time: 9 msec
;; SERVER: 195.188.99.250#53(195.188.99.250)
;; WHEN: Tue Jul 20 18:25:44 2010
;; MSG SIZE  rcvd: 105


Tony.
-- 
f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
PORTLAND PLYMOUTH BISCAY: WEST OR SOUTHWEST 3 OR 4, INCREASING 5 AT TIMES.
MODERATE, OCCASIONALLY SLIGHT IN PORTLAND. RAIN OR SHOWERS, FOG PATCHES AT
FIRST. MODERATE OR GOOD, OCCASIONALLY VERY POOR AT FIRST.