host statement scope rules (ISC DHCP 3.0.5b1)

David W. Hankins David_Hankins at
Mon Jul 31 15:17:52 UTC 2006

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.

David W. Hankins	"If you don't do it right the first time,
Software Engineer		you'll just have to do it again."
Internet Systems Consortium, Inc.	-- Jack T. Hankins

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