host statement scope rules (ISC DHCP 3.0.5b1)

Sten Carlsen sten at
Tue Aug 1 16:20:09 UTC 2006

While nobody WANTS to mess things up like here, it could happen by
mistake. E.g. I start with one subnet and for readability puts my host
statements here. Then I expand with another subnet and a different set
of host statements. At some stage one of these hosts or by repair only
the netcard moves to the other subnet. Things have stopped working and I
have done nothing. This needs a heavy warning, that possibly could be
disabled if you really know what you are doing; but then your repairman
may not know that.

Bruce Hudson wrote:
>> 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

Best regards

Sten Carlsen

No improvements come from shouting:


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