Mapping a MAC to an IP...
dhcp1 at thehobsons.co.uk
Wed Jan 21 17:12:52 UTC 2009
Peter Laws wrote:
>>Host declarations are global in scope, and so are valid even if a
>>client is connected to a different subnet (in which case it will
>>get a dynamic address from that subnet rather than the fixed
>>address). But what would happen is that the client would get a
>>suitable IP address, but inherit options (such as routers) from the
>>subnet where the host statement is declared - I think you can
>>imagine the confusion that causes !
>That makes no sense ... if a particular host connects to a
>different subnet, I'd want it to get the information *appropriate
>for that subnet*, not the one where it may have a static
>IP/reservation/whatever you want to call it. What am I missing?
It's only a problem if you declare a host statement inside a subnet
declaration - I think it also applies with class declarations as
well. As long as you put your host statements in the global scope (ie
not inside a subnet declaration) then they will work as you would
It's a side effect of the way inheritance works, and probably
something not envisaged when the original design was done. If you put
a host statement inside a subnet, it inherits options (eg routers)
from that subnet, but since it is a global object it is still
recognised when the client is in a different subnet - and hence you
find a client getting options that are inherited from a different
The safe thing to do is to keep all your host (and class)
declarations in the global scope - then you don't need to worry about
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