host statement scope rules (ISC DHCP 3.0.5b1)

Sten Carlsen sten at
Mon Jul 31 16:42:25 UTC 2006

I am sorry, I have to be a little slow to get this. Can we assume (for
the discussion) that I have 2 subnets with slightly different settings
(e.g. different DNS servers):

Situation 1) Host statement outside both subnets.
Situation 2) Host statement inside subnet A.
Situation 3) Host statement inside subnet B.

I connect host to subnet A-port. Will I have DNS server A in all three
cases or will I have DNS server B in situation 3)?

Or is this wildly misunderstood?

David W. Hankins wrote:
> On Sun, Jul 30, 2006 at 02:04:10AM +0200, Sten Carlsen wrote:
>> If I understand this correctly You say that there is a difference
>> between placing a host statement in the global scope (i.e. outside all
>> subnet statements) and placing the host statement within a subnet
>> declaration.
> I've just been down this maze of twisty passages, and now I think
> I know how to expose this second truth in the simplest, easiest to
> understand manner:
> The subnet {} clause is implicitly also a group {} clause.  So all
> host statements within the subnet {} clause share a group that is
> anchored at the subnet's curly braces.  The same is true of the
> shared-network {} clause, it is also implicitly a group {}.
> What's left for this thread is to decide consensus about how best
> to illustrate these two pieces of information to novice users.
> Currently, 3.1.0 as it exists on our release branch will produce
> a single-line warning (no matter how many host records you have)
> with the following text:
> 		log_error("WARNING: Host declarations are "
> 			  "global.  They are not limited to "
> 			  "the scope you declared them in.");
> There aren't enough cycles between now and 3.1.0's release to
> add an option to remove this warning, as has been requested.
> Our options for 3.1.0's schedule are to go ahead as it is, to
> reword it, or to remove this 'feature' entirely.
> Please provide some feedback on what you'd like to see in 3.1.0.

Best regards

Sten Carlsen

No improvements come from shouting:


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