DDNS fails. record allready exists

Mark Andrews marka at isc.org
Thu Dec 23 01:00:17 UTC 2010

This is a DHCP issue and I would be re-asking on the dhcp list if
the explantion below is not enough.  Named is just honouring what
is in the update requests.

dhcpd trys to ensure it doesn't clobber records it doesn't have
change control for.  From memory it does this with a new lease by
asking is there a A record for the name and having the update abort
if it is there.  If this update fails it makes a second update
request this time looking for a TXT record with known content
specific to the DHCP server and the update succeeds if that is
there.  See below for a example for a example of the TXT record it
looks for.

By shutting down overnight I suspect you are triggering the new
lease processing as the DHCP server isn't running when the lease
expires.  As long as the address record gets added by one of the
update requests there is no problem, just a bit of noise in the


; <<>> DiG 9.6.0-APPLE-P2 <<>> any BRNEE8E63.dv.isc.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 8499
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 2, ADDITIONAL: 1

;BRNEE8E63.dv.isc.org.		IN	ANY

BRNEE8E63.dv.isc.org.	1800	IN	A
BRNEE8E63.dv.isc.org.	1800	IN	RRSIG	A 5 4 1800 20110129005954 20101130000256 14436 dv.isc.org. v5G+lPmaHfEJp5qSN0JiJJagrj7HPff5nblelsu/oEB5nXh8MCJVZb9W 7qGlO3q/Jmj+4N21ADErCKecmipGyQ==
BRNEE8E63.dv.isc.org.	1800	IN	TXT	"3115c8fab3a3b80243bfe8be9b83182565"
BRNEE8E63.dv.isc.org.	1800	IN	RRSIG	TXT 5 4 1800 20110129005954 20101130000256 14436 dv.isc.org. 2bPfwxfWpZ7omD7Vd9VfFrSbV1nCiTfF3ymPhudG+rF6g9ms/81zyEVV B+vhzS8KUj3O1AixECdnTMljYI9FYA==
BRNEE8E63.dv.isc.org.	86400	IN	NSEC	bsdi.dv.isc.org. A TXT RRSIG NSEC
BRNEE8E63.dv.isc.org.	86400	IN	RRSIG	NSEC 5 4 86400 20110129005954 20101130000256 14436 dv.isc.org. 0KHHF6xjPqyo5ps31BP2PI6lQ3AAW8n8gVmoc4ijTFB5/rzUN2gw86Ug GFRiCTirEbXdDX5lnJZ9sj3oG4qzeQ==

dv.isc.org.		86400	IN	NS	drugs.dv.isc.org.
dv.isc.org.		86400	IN	NS	bsdi1.dv.isc.org.

bsdi1.dv.isc.org.	86400	IN	A

;; Query time: 0 msec
;; WHEN: Thu Dec 23 11:46:26 2010
;; MSG SIZE  rcvd: 512

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org

More information about the bind-users mailing list