Subject: DHCP client

From: "Todd Wasielewski" <[email-masked]>
Date: Wed, 23 Feb 2000 20:15:38 PST

I've been researching DHCP for three days and still don't have an answer to 
my question.

I have a windows95 machine running microsofts DHCP client.  I have an NT 
server running the DHCP server.   My lease is for 3 months.

My question is;   I turn on my PC and obtain an IP address.  I turn off the 
DHCP server, I still have that DHCP address until the lease expires correct? 
    Now the DHCP server is still off.  I shutdown my windows95 PC with the 3 
month lease and turn it off.   When I turn the PC on should I or should I 
not have a valid IP address on it for imediate use?   I say no because the 
DHCP server is down and everytime the client starts it needs to talk with a 
DHCP server.

I read tons of MSDN notes and in my office I tested it and it worked like 
that.   But my colleagues in NY mention they can turn off their DHCP server 
and reboot their workstations and still have an IP address which was 
intially assigned by DHCP in use.

I even read the DHCP RFC's and it was confusing because;

.7 When clients should use DHCP

   A client SHOULD use DHCP to reacquire or verify its IP address and
   network parameters whenever the local network parameters may have
   changed; e.g., at system boot time or after a disconnection from   the 
local network, as the local network configuration may change without the 
client's or user's knowledge.

   If a client has knowledge of a previous network address and is unable to 
contact a local DHCP server, the client may continue to use the previous 
network address until the lease for that address expires.
   If the lease expires before the client can contact a DHCP server, the
   client must immediately discontinue use of the previous network
   address and may inform local users of the problem.

and this paragraph;

4.4.6 DHCPRELEASE

   If the client no longer requires use of its assigned network address
   (e.g., the client is gracefully shut down), the client sends a
   DHCPRELEASE message to the server.  Note that the correct operation
   of DHCP does not depend on the transmission of DHCPRELEASE messages.

PLEASE HELP ME SEE THE LIGHT!!!!!
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From: Michael Schneider <[email-masked]>
Date: Thu, 24 Feb 2000 21:27:41 -0600

Todd -
  My WINTEL experience in this matter is thus:

If:
A) Client receives lease (lease period is 90 days), and
B) DHCP server dies, and 
C) DHCP stay dead for more than 90 days.
Then:
D) At each start up and at every decaying half-life interval,
the client will poll the nonexistent DHCP server for a renewal
of the lease it has. If the lease expires before the DHCP service
is restored, the client should lose its IP address, and continue
to periodically broadcast DHCP requests until it receives a response.

Anyone feel free to correct me.

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Michael Schneider                                  Sr. Network Engineer
                           [email-masked]
		 McKessonHBOC at Evanston Hospital
http://wwp.mirabilis.com/1954898                       ICQ UIN: 1954898
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