A dumb DHCP question

  • Thread starter Thread starter Paul Fritz
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Paul Fritz

Hi all,

This is driving me crazy! If I have a DHCP server with a
scope for each subnet, how does the DHCP server know
which scope to pull a configuration from when it recives
an initial request from a client? In other words, what
prevents it from leasing an IP address, subnet mask, and
default gateway from the wrong scope?

Thanks in advance!
 
THANK YOU!

I feel much better now.....
-----Original Message-----
Well, if the client is on the same subnet its done through means of
broadcast as I am sure you are aware.

Simply put:
If the client is on the other side of a router then the router must be
specially configured as an "ip helper" (in Cisco talk) or relay agent which
will effectively pass the clients DHCP broadcast from the client to the DHCP
server on the other subnet. The router or relay agent will include its IP
address in the DHCP request. When the DHCP server receives this request it
determines (because of the presence of the router's ip address) which subnet
the client belongs to and what appropriate address range to use.

See http://www.faqs.org/rfcs/rfc1542.html for detailed information.




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