DHCP client state if rebooted when local DHCPD server is offline?

Simon Hobson dhcp1 at thehobsons.co.uk
Thu Aug 14 22:22:22 UTC 2014

Gregory Sloop <gregs at sloop.net> wrote:

> As a follow-up. I know that some Windows machines will continue to hold the unexpired lease over a reboot, and that to force a check with the DHCP server you'll have to do a ipconfig /release | ipconfig /renew to do so.
> So, in practice, in at least some versions of Windows, they will continue to hold the lease.

Yes, Windows clients are "quite tenacious" about keeping their address. In part, this is how MS make their server/client combination stable since the server isn't RFC compliant. Basically, MS make the client attempt to get it's previous address rather than making the server remember things properly. From their POV this is fine since non-Windows servers or clients don't exist :-/

From memory, Macs do several ARP requests for the previous default gateway and will continue to use a non-expired lease if still valid (and no DHCP server replies). I think Windows does the same.

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