[ddns] "update-conflict-detection" and co-existing DHCPv4/v6 servers

Chuck Anderson cra at WPI.EDU
Sat Mar 24 14:34:04 UTC 2012

On Fri, Mar 23, 2012 at 08:41:46AM +0100, Peter Rathlev wrote:
> On Thu, 2012-03-22 at 19:16 +0000, Eustace, Glen wrote:
> Just to make this clear: Disallowing client updates as such does not
> prevent clients from having arbitrary names put in DNS. And since most
> DHCP server configurations do not validate the client supplied name at
> all, the client can pretty much decide for itself what name it wants,
> even though the DHCP server technically does the updating.
> Using "host" entries means the DHCP server simply doesn't perform the
> dynamic update at all, unless you use the "update-static-leases"
> parameter. And without either a "host-name" option in each static
> decleration or the "use-host-decl-names" parameter I would think that
> the client supplied name is still used.
> Client supplied names is a real issue.

You can configure the DHCP server to override client supplied names on
dynamic leases with either "host" statements without fixed-addresses,
or by using classes/subclasses.

ddns-hostname "agoodname";
ddns-domainname "example.com";

Then the server will update both forward and reverse DNS using that

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