xp dhcp client feature

[Agostino Sclauzero]

I've read (Microsoft Windows Server 2003 Inside Out) that dhcp clients such
as the one implemented in win xp, before going apipa, tests if the default
gateway is reachable.

If the default gateway is still reachable, a win xp (configured with dhcp)
will mantain its ip address, also if there are no more dhcp servers on the
subnet to renew the lease.

This is a very smart behaviour, but sometimes i sperimented the opposite: at
the end of the lease period a client takes an apipa address, while it's in
the same subnet and the gateway is still reachable (obviously there's no
more dhcp server, of course).

Anyone has faced this problem, doing more testing?
thanks in advance
Agostino

 

[John Wunderlich]

I've read (Microsoft Windows Server 2003 Inside Out) that dhcp
clients such as the one implemented in win xp, before going apipa,
tests if the default gateway is reachable.

If the default gateway is still reachable, a win xp (configured
with dhcp) will mantain its ip address, also if there are no more
dhcp servers on the subnet to renew the lease.

This is a very smart behaviour, but sometimes i sperimented the
opposite: at the end of the lease period a client takes an apipa
address, while it's in the same subnet and the gateway is still
reachable (obviously there's no more dhcp server, of course).

Anyone has faced this problem, doing more testing?
thanks in advance
Agostino

The IP address is "owned" by the DHCP server and leased to your
computer client for a period of time. Starting when the lease period
is 1/2 over, the client attempts to renew the lease. If the lease
period expires without the DHCP server agreeing to a renewal, then the
client machine MUST immediately stop using that IP address (does not
matter whether there is a gateway there or not). At that point in
time, apipa is the only option remaining.

HTH,
John