"name not in use" prerequisite for ddns updates

Simon Hobson dhcp at thehobsons.co.uk
Thu Jun 1 15:04:15 UTC 2006

Karl Mueller wrote:

>I was wondering if there's any way to remove the prerequisite "name does not
>exist" for dynamic A records in the interim-style DDNS update method. I have
>isc dhcpd and bind 9 working together for DDNS, but because of the way I'm
>handing out leases, I want the newest name for a client to always win and be
>updated, no matter what (I'm using the dhcp server as a back-end to a VPN
>concentrator who acts as a dhcp proxy). I thought about using ad-hoc, but
>apparently it's not supported any more.

You would have to edit the source and remove the test - I wouldn't 
imagine it's hard.

Be aware that the test is there for security - without it, someone 
can name their client "server" (or whatever your important machine is 
called), and suddenly they take over the a record for the server that 
your business relies on. If you don't mix dynamic clients with fixed 
servers in the same dns zone then that won't be a problem.


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