deny client-updates and ddns-updates

Rafael Darder Calvo rdarder at
Mon Mar 23 22:10:13 UTC 2009

I have some doubts regarding the dhcp server behaviour when configured to do
dns updates. I have read the manuals and googled for a while but something
remains unclear to me.

Some of my current settings in dhcpd.conf:

ddns-updates                on;
do-forward-updates          on;
ddns-update-style           interim;
ddns-domainname             "";
ddns-rev-domainname         "";
deny    client-updates;
update-static-leases        on;
update-optimization off;
use-host-decl-names on;

So, when a dhcp client sends a fqdn in its request, the server ignores the
provided fqdn and uses the "option host-name"  defined in the host
declaration to update my dns server, which is fine since I put "deny

On the other hand, if the client doesn't send a hostname, no dns update is
performed at all, even if the host declaration has an "option host-name".

Is this the correct behaviour? I can't deduce it from the dhcpd.conf manual.
If it's the case, is there any way I can force dhcp server to update the dns
records even if no fqdn is sent in the client request?


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