host statement scope rules (ISC DHCP 3.0.5b1)

Simon Hobson dhcp1 at
Fri Jul 28 12:41:43 UTC 2006

Phil Pennock wrote:

>  >			Changes since 3.0.4
>>  - A warning that host statements declared within subnet or shared-network
>>    scopes are actually global has been added.

>Whilst the host statement is matched at a global level, aren't
>attributes such as lease time values inherited based upon syntactic
>scope rather than address/netblock matching rules?
>We have generated configs which use host statements inside subnet
>scopes, knowing full well that the host statements are matched globally
>but wanting to be able to inherit values based upon which relay server
>sent data to us.
>If ISC's dhcpd is inheriting values based upon address matching, then
>can someone please state if this has always been the case and, if not,
>which version introduced it?

I always though that clients matching host statements inherited 
options based on the subnet to which the client got assigned - which 
would appear to be the same as inheriting them based on where the 
host statement was written IF that matched where the client got 

If you always get the host statements in the right place, it would 
look like the organisation of the config file was causing the 
inheritance - as in it's the host declaration that's inheriting the 
options. In fact, I think you'll find that clients inherit options at 
lease time based on their subnet, not on where the host declaration 
is written.

More information about the dhcp-users mailing list