two dhcp server on a subnet

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Jan 29th, 2009
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Hi every body!

Let say we have two dhcp server s1 and s2 and single host on a subnet.

Let say host sends broadcast dhcp req, s1 receives the request before s2,,

s1 sends the dhcp reply to host, host receives dhcp reply from s1 and sets its ip address and default gateway as specified in dhcp reply from s1. After a while, s2 sends the dhcp reply in response to dhcp request from host.

what would host do? will it ignore the s2 dhcp reply or it will process the reply and use the new setting specified in dhcp reply from s2.

thanks a lot!

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Roberto Salazar Thu, 01/29/2009 - 16:52
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I am not sure whether that offer will be ignored or dropped but the host already have an ip address, given that the host already accepted that ip address, it will retain that offer it accepted from the server that responded first.

Richard Burts Thu, 01/29/2009 - 19:38
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To supplement the reply from Roberto, s1 sends a dhcpoffer and the client accepts it. Then s2 sends a dhcpoffer which the client ignores since it already has an address. s2 waits for a response to its dhcpoffer, does not get a response, times out the dhcpoffer, and returns the address that it offered to its pool of available addresses.




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