host statement scope rules (ISC DHCP 3.0.5b1)

Randy Grimshaw rgrimsha at
Tue Aug 1 12:53:07 UTC 2006

I agree with the suggestion that a list of static addresses also include
a wildcard to denote that the host can also participate in dynamic
assignments in other subnets.
This would cut our configuration file nearly in half.
The reason I can see the need for a list is the increase in mobile
devices that require security assigned to an IP (due to
limitiations imposed by other applications and perhaps the increased
trustworthyness in 802.1x).

<><Randall Grimshaw
Room 203 Machinery Hall
Syracuse University
Syracuse, NY   13244
rgrimsha at

>>> Bruce.Hudson at Dal.Ca 8/1/2006 8:38:44 AM >>>
> Is there any real reason to need the inheritance of putting a host 
> declaration within a subnet ? I guess it comes down to, will the host

> inherit anything that it wouldn't have inherited anyway by virtue of

> being 'put there' as the server allocates it to a subnet for lease 
> allocation purposes ?

    If I recall complaints from a while ago correctly, the answer has
been known to be yes. There was list traffic discussing a host declared

within a subnet, using a dynamic address on another subnet, that was
incorrectly inheriting and using parameters from the first subnet. I
cannot think of any setup where somebody would want to do this: give
parameters to any host using a network adddress AND any of a set of
hosts no matter where they are used. I suppose it is possible somebody
might want to do it on purpose in the name of "efficiency" -- to avoid
duplicating a few statements in an explicit block.
    Unfortunately I cannot find the messages I am thinking of and I do
not recall whether the syntactic declarations were over-riding those
provided by the subnet used or just providing parameters that were not
supposed to be configured at all in that context.
Bruce A. Hudson				| Bruce.Hudson at Dal.CA 
UCIS, Networks and Systems		|
Dalhousie University			|
Halifax, Nova Scotia, Canada		| (902) 494-3405

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