dns_update_log shows dynamic entries deleted

[dave c]

Well, you are likely asking the wrong side of the equation.

If I had to venture a guess, your DNS server reloaded itself.

Dynamic DNS updates are written to a local cache for the zone. I don't know if that cache will 
always persist through having DNS restarted, but I'd suggest that as it's dynamic, it's not 
designed to be persistent in the DNS zone. Otherwise it would be in a DNS zone file :)

Do you have any info or stats on the DNS side of things?

If you had said that you started seeing updates not getting through to DNS, then I'd suggest 
that the issue might be that the DHCP system and DNS system had a change in what they used to 
authenticate updates. But as all dynamic DNS information departed at the same time and is being 
recreated as systems check into DHCP, it points to the issue being on the DNS side.

Dave

On 6/9/15 13:21, Cuttler, Brian (HEALTH) wrote:
> I disabled update_optimization and as dhcp releases are renewed (I already has update_static
> enabled) we are re-creating the DNS entries.
>
> I still have no idea why those entries all got deleted and am rather stressed over it.
>
> Please help me to understand what went wrong, and how to prevent or properly fix.
>
> Many thanks,
>
> Brian
>
> *From:* dhcp-users-bounces at lists.isc.org [mailto:dhcp-users-bounces at lists.isc.org] *On Behalf Of
> *Cuttler, Brian (HEALTH)
> *Sent:* Tuesday, June 09, 2015 12:05 PM
> *To:* Users of ISC DHCP
> *Subject:* dns_update_log shows dynamic entries deleted
>
> We are running on Centos 7.1 and have dhcp 4.2.5, with bind 9.9.4.
>
> We are running dhcp with subnet 10.57.36.0/22 permitted dynamic dns udpates, except for the last
> 100 addresses in the pool, which we excluded to allow for static addresses that we needed.
>
> Things have been working wonderfully – but at 08:18 this morning a large number of entries were
> removed from dynamic dns.
>
> The dhcp clients were either, only asleep for the night (Windows, printers) or actually online
> (linux).
>
> I’ve no idea why these DNS entries were removed, exactly how to get them back, and how to
> prevent them from being removed again.
>
> I’d suspect it was a lease expiration issue, but these machines all check in and renew, at least
> they should be, I can check the boot.log and see.
>
> Thanks for your help,
>
> Brian
>
>
>
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-- 
Dave Calafrancesco