From: Randall Parker 

I'm wrestling with a problem of communication between a Linux device and a Windows
box where the Linux device acts as a DHCP server and have some questions that I'm
hoping might shed light on my problem:

1) When a DHCP server provides a lease of an IP address for some period of time t1
(e.g. 30 minutes) does the client box that asked for the lease always try to renew it
when it is only halfway (e.g. t1/2 or 15 minutes) toward timeout? Is that a standard
behavior across operating systems?

2) If a Windows box tries to renew a lease and gets no response back then does it
retry? If so, how many times?

3) Does lease renewal start at DHCPDISCOVER or at the later point of DHCPREQUEST? Is
the answer to that question standard across operating systems?
http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol

4) If a Windows box attempts to renew at the halfway point (e.g. t1/2 or 15 minutes
on a 30 minute lease) and fails to do so does it continue to use the IP address until
it expires or does it decide right then that the address is invalid?

5) How long does a Windows box wait for a response to a DHCPDISCOVER before trying
again or marking the IP address as invalid? Is that configurable?

6) When would you expect ifconfig to no longer show a leased address for an
interface:  A) when the halfway point renewal fails or B) when the lease
period finally expires or C) some other time?

7) Are the rules for the above any different when using ethernet versus, say, RNDIS
over a USB bus?

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