Reply to remote unicast DHCP requests

Simon Hobson dhcp1 at
Tue May 3 11:21:10 UTC 2011

Paúl Ortiz Imedio wrote:
>I am trying to figure out the behaviour of the DHCP server when replying to
>unicast DHCP Requests from clients at remote subnets (RENEWING state).

It's quite simple. The server should reply by 
unicast to the client. The packet is routed via 
normal OS routing rules.
When you say the server is not responding - does 
it log the request ? Does it log that it's 
replying ? Does it have a route to the client's 
network ?

For details of how the protocol works, I 
recommend "The DHCP Handbook"  by Ralph Droms and 
Ted Lemon. There's a second edition which covers 
failover, but for the basics the original edition 
will do fine if you can't find the newer one.

Simon Hobson

Visit for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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