DHCP Lease Duration

[Monte W]

We are looking to make our DHCP in a windows 2000 environment more fault
tolerant. Currently we have only one DHCP server. I am aware of the best
practice of two DHCP servers with 75% of the addresses on one server and 25%
of the address on another Server. The deal is that we are mostly
centralized with AD, DNS, WINS, DHCP at our central location. We do have
some critical application servers at remote locations. It appears to me
that a windows 2000 pro client with a 8 day DHCP lease will loose it's IP on
a reboot even if it's lease has not expired. So they might be able to log
in using cached credentials but they do not have an IP to get to local
resources/application servers. Is their a way to make a 2000 pro client
keep it's IP if it reboots and does not find a DHCP server so long as it's
IP has not expired? Thanks in advance.

Monte Watembach

 

[Chris Knapp]

Unfortunately, after a reboot, if the client can't detect a DHCP server it
will generate a random IP from the 169.254.X.Y auto address range. One trick
I saw once: The admin configured his remote server with a 2nd IP of
169.254.0.1 (mask 255.255.0.0) so that when his link to HQ went down &
clients lost IP's, they could still see the server in his office. Never
tried it myself though. . .

 

[Danny Slye - [MSFT}]

I am not sure exactly what you are asking but a Windows 2000 DHCP client
performs the following procedure when it reboots:
It attempts to renew it's lease with it's DHCP server by sending a
DHCPRequest packet
If it's DHCP server responds with a DHCPAck, it renews it's lease,
If the DHCP server responds with a DHCPNack, it starts the lease process
all over
If it's DHCP server does not respond, it pings the default gateway defined
in it's current lease
If the ping succeeds, it continues to use it's current lease, attempting to
renew at 50% of it's assigned lease time
If the ping fails, it auto-configures the IP address and continues to
attempt to find a DHCP server in the background.
Hope this helps

--------------------

Unfortunately, after a reboot, if the client can't detect a DHCP server it
will generate a random IP from the 169.254.X.Y auto address range. One trick
I saw once: The admin configured his remote server with a 2nd IP of
169.254.0.1 (mask 255.255.0.0) so that when his link to HQ went down &
clients lost IP's, they could still see the server in his office. Never
tried it myself though. . .

__
Danny Slye
Microsoft Support Professional
MCSE

This posting is provided "AS IS" with no warranties and confers no rights.
Please reply to the newsgroup so that others may benefit. Thanks!

 

[Marc Reynolds [MSFT]]

Check the registry and see if you have a "ReleaseOnShutDown" key. By
default
the key should not be there and the default behavior is to Release On
Shutdown Obey
DHCP Server.
[HKLM\System\CurrentControlSet\Services\TCPIP\Parameters\Interfaces\<adapter
_gu
id>] ReleaseOnShutDown = (REG_DWORD) with the possible values:

0 (RELEASE_ON_SHUTDOWN_NEVER) - don't release the lease on shutdown

2 (RELEASE_ON_SHUTDOWN_OBEY_DHCP_SERVER) - release or leave the lease
depending
on what the server instructed (OPTION_MSFT_VENDOR_FEATURELIST:
BIT_RELEASE_ON_SHUTDOWN).

Anything else (RELEASE_ON_SHUTDOWN_ALWAYS) - release the lease on shutdown
If the
reg key is missing, it defaults to
RELEASE_ON_SHUTDOWN_OBEY_DHCP_SERVER.

The DHCP Server could also be sending the option to Release on Shutdown if
you have configured this with User Classes.

Thanks,
Marc Reynolds
Microsoft Technical Support

This posting is provided "AS IS" with no warranties, and confers no rights.