Multiple matching dhcpd.conf MAC addresses

Dean Gibson (DNS Administrator) isc at
Sun Mar 31 01:24:48 UTC 2013

Ah, thanks!  In your 3rd paragraph below, only the first sentence of it 
is present in my dhcpd.conf MAN page;  That confirms the details of the 
2n paragraph.  I'm (gasp) running dhcp v3.0 (CentOS 4.4), but my guess 
it that it's the same code.  I made the changes to dhcpd.conf and 
restarted;  we'll see what happens ...

-- Dean

On 2013-03-30 11:45, Sten Carlsen wrote:
> From the MAN page:
> The *host* declaration provides a scope in which to provide 
> configuration information about a specific client, and also provides a 
> way to assign a client a fixed address. The host declaration provides 
> a way for the DHCP server to identify a DHCP or BOOTP client, and also 
> a way to assign the client a static IP address.
> If it is desirable to be able to boot a DHCP or BOOTP client on more 
> than one subnet with fixed addresses, more than one address may be 
> specified in the /fixed-address/ declaration, or more than one *host* 
> statement may be specified matching the same client.
> If client-specific boot parameters must change based on the network to 
> which the client is attached, then multiple *host* declarations should 
> be used. The *host* declarations will only match a client if one of 
> their /fixed-address/ statements is viable on the subnet (or shared 
> network) where the client is attached. Conversely, for a *host* 
> declaration to match a client being allocated a dynamic address, it 
> must not have any /fixed-address/ statements. You may therefore need a 
> mixture of *host* declarations for any given client...some having 
> /fixed-address/ statements, others without.
> Seems to be perfectly viable.
> On 30/03/13 18:26, Dean Gibson (DNS Administrator) wrote:
>> If I have two (distinct/unique) "subnet" declarations, and have two 
>> "host" declarations with the same "hardware address" but different 
>> "fixed-address" values, with one "fixed-address" matching the first 
>> "subnet" declaration, and the other "fixed-address" matching the 
>> second "subnet" declaration, will this work properly ?
>> I would like to have the same host be able to physically move from 
>> one subnet to the other, without having to change the dhcpd.conf file 
>> and restart the dhcpd servers.

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