Any way to query/list "Negative" Records
Mark Andrews
marka at isc.org
Thu Feb 11 00:14:06 UTC 2010
In message <201002102002.40279.jorge.fabregas at gmail.com>, Jorge =?iso-8859-1?q?
F=E1bregas?= writes:
> Hello everyone,
>
> Today I had an issue with one of our caching nameservers (it wasn't presentin
> g
> a recently created MX record). I didn't know whether the server had any
> problem requesting this record upstream or someone queried for this record
> before it was created causing the server to cache the 'negative' result. I
> presumed it was the latter and proceeded to manually flush the particular
> domain. After that it worked.
>
> But... I'm wondering: Is there a way (using dig or rndc) to list the
> "negative" records the server has in its cache? I guess I could dump the cach
> e
> contents and see it there (haven't tried it) but was wondering if there's a
> proper way to do this (instead of just presuming "the server cached the
> negative answer...").
>
> Best regards,
> Jorge
> _______________________________________________
> bind-users mailing list
> bind-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/bind-users
You can see a cached negative response by looking at the TTL of the SOA
record. When that hits zero the cached negative response will be removed.
See RFC 2308.
; <<>> DiG 9.3.6-P1 <<>> type100 isc.org
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27586
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;isc.org. IN UINFO
;; AUTHORITY SECTION:
isc.org. 2209 IN SOA ns-int.isc.org. hostmaster.isc.org. 2010020700 7200 3600 24796800 3600
;; Query time: 250 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Feb 11 11:10:48 2010
;; MSG SIZE rcvd: 79
; <<>> DiG 9.3.6-P1 <<>> type100 isc.org
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31619
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
;isc.org. IN UINFO
;; AUTHORITY SECTION:
isc.org. 2203 IN SOA ns-int.isc.org. hostmaster.isc.org. 2010020700 7200 3600 24796800 3600
;; Query time: 11 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Feb 11 11:10:54 2010
;; MSG SIZE rcvd: 79
--
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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