Two offers in response to one discovery

Simon Hobson dhcp1 at thehobsons.co.uk
Wed Dec 14 15:51:03 UTC 2011


John Miller wrote:

>What I am seeing in a pcap is the WindowsXP client, after a 
>release/renew, send the discovery and the server responding with 2 
>offers of 2 different IP addresses. First question is does this seem 
>to be any kind of normal behavior? Second question is what 
>additional information do I need to provide to help resolve this 
>issue?

This can happen is there are two paths for a request to reach the 
server - eg two routers on redundant paths both acting as relays. 
However, in that case, you should see the same IP address in the two 
offers.
Alternatively, someone has setup a rogue server.

You would want to examine the contents of the offer packets, and see 
what the Server ID field holds.
-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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