DDNS Update Forwarding

Mark Andrews marka at isc.org
Mon Oct 10 00:26:57 UTC 2016

In message <CA+huvoqJFHKbRVhMDkKasUesg-0TNf3LXuVdEqA4VFiycDsKmQ at mail.gmail.com>, Mark Mc Nicholas v
ia bind-users writes:
> Hi List,
> I have a number of small sites which all vpn to a core site where the
> authoritative dns servers live.
> The sites all have their own DHCP server and slave dns servers. Currently
> DDNS updates are sent from
> the local dhcp servers to the central servers which is working fine.
> However something occurred recently
> where the VPN linking the site was down for a number of days. This ment the
> DHCP server wasn't able to update
> forward and reverse zones. Which means the updates removing stale records
> never made it to the authoritative servers.
> If I change the the DHCP servers to send DDNS updates to the local slaves
> servers with allow-update-forwarding enabled, and the vpn drops again will
> the will the slave servers queue the updates until the link to the masters
> is reestablished?
> Sorry for the long winded email and thanks for any input
> Kind Regards
> Mark

Update forwarding is designed so you can talk to any listed nameserver
and have the request forwarded to the master.  This is real-time
forwarding, not store and forward.

The real question is why the masters servers for the reverse zones
and presumably the local forward zones are centralised.  Best
practice would have the masters at the remote site so that the site
can operate when the external links are down.

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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