multiple subnets same ddns zone

Simon Hobson dhcp1 at
Fri Aug 28 13:33:31 UTC 2009

Glenn Satchell wrote:

>  >Should the zone definitions get defined inside the subnet or do 
>they get placed
>in the global scope?
>Whether you have one subnet or many, you only need one declaration for
>each zone, and that should typically be in the global scope.

Just to add to that, you are NOT defining zones as 'attached' to any 
specific subnet. If you don't use key-based updates security then you 
don't even need any zone definitions (assuming your DNS setup is not 
broken) as the DHCP server will use (IIRC) the SOA record to identify 
the master to send updates to.

ddns-domainname sets the forward zone used for updates, and as Glenn 
says, the defaults should normally work for reverse (PTR) updates.

The zone definitions are only required (in the global scope) to 
provide two bits of information : the key, and the server to send 
updates do.

As an aside, does the server need to be specified ? Eg, is it 
sufficient to have :
zone {
   key <key>;
and have dhcpd determine the master automatically ?

Simon Hobson

Visit for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

More information about the dhcp-users mailing list