Dual DNS server farms in dhcpd.conf

Simon Hobson dhcp1 at thehobsons.co.uk
Tue Apr 28 18:29:59 UTC 2009

John Tabasz (jtabasz) wrote:

>So I understand properly,  when you say putting
>the host statements inside a scope other than global isn't generally a
>good idea, you are referring to the shared network scope plus the second
>scope of the subnet, right?

Exactly. In your config, the host statements are inside the 
shared-subnet - a case we haven't come across before so I'm not 
entirely sure what happens here. A couple of times, user have put 
host statements inside a subnet declaration (erroneously) thinking 
that this would make the statement valid only within that subnet. 
They've them come to the list wondering why a client gets an IP 
address, but other options (such as routers !) from the wrong subnet 
when the client is connected elsewhere.

What's happened in that case is that the client gets an IP according 
to the subnet where it is connected, but inherits options from the 
subnet where it's declared. Hence we keep advising to keep host 
statement in the global scope.

I think in your case it **probably** isn't an issue since there are 
no options declared at the shared-network level - but best to avoid 
it anyway.

Simon Hobson

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