Subnet, Pool, and Zone Declarations

Chris Buxton cbuxton at
Mon Nov 9 23:27:00 UTC 2009

The documentation of the syntax of dhcpd.conf seems to be quite thin  
and vague, depending more on examples than reference data. Therefore,  
if the syntax you have used works, then it's probably correct - or at  
least there's no definitive way to disprove it.

However, as a member of the team supporting an IPAM solution such as  
you describe, I can say that our development team has had a very  
difficult time trying to accommodate all possible combinations of  
statements in dhcpd.conf. Therefore I'm not surprised that your  
vendor's product has trouble with the syntax you've used - nowhere in  
the dhcpd.conf manpage does it say that it is valid to declare a zone  
inside another declaration.

Chris Buxton
Professional Services
Men & Mice

On Nov 7, 2009, at 9:30 AM, Merton Campbell Crockett wrote:

> Can a zone declaration appear within a pool or subnet declaration?
> My company acquired an IP Address Management (IPAM) system.  One of  
> its features is that it provides a place to store information about  
> a system that, normally, would not be in a DNS zone file.  Another  
> is that it provides a safe way to allow server administrators and  
> site support personnel to make DNS changes.  Another feature is that  
> it allows IT and Security personnel to see the DHCP lease  
> assignments and identify which IP addresses are currently leased and  
> by what systems.
> My question involves this last feature.  At several sites, I have  
> included a zone declaration inside a subnet or pool declaration.   
> The rationale for doing this was that the zones were unique and only  
> to be used for systems that were leased addresses from the subnet or  
> pool.  DHCP 3.1.2p1 accepts this construct.
> The vendor of the IPAM system has done a relatively good job of  
> ensuring that the IPAM system conforms to DNS and DHCP standards;  
> however, it won't process DHCP lease information when there is a  
> zone declaration within a subnet or pool declaration.
> Is my usage of zone declaration within a subnet or pool declaration  
> valid?  Does the vendor of the IPAM system have a "bug" in its  
> implementation that needs to be corrected?
> Merton Campbell Crockett
> m.c.crockett at
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> dhcp-users mailing list
> dhcp-users at

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