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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