Re: DHCP processing

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Thank you Bill.

That means, if the client boots and no DHCP server is available, the client
use its IP address lease obtained on a previous occasion, if the lease is
valid. If the lease is invalid, the client configures an APIPA address.

regards
chris



"Bill Grant" wrote:



"chris" <chris@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:CEC966D1-0A36-4343-B2F5-703F74D1F5C8@xxxxxxxxxxxxxxxx
Hi
I am learning for MCITP and I am confused with DHCP processing. I have a
DHCP server and a DHCP enabled client. The client obtained its IP
configuration (IP address, gateway, DNS) from the DHCP server. What
happens
now, if I restart the client and the DHCP server is unavailable?

http://technet.microsoft.com/en-us/library/dd183602(WS.10).aspx says:
If the client has a valid IP lease and the DHCP server is unavailable
during
the client restart, the client pings the gateway. If the ping is
successful,
the DHCP client assumes that it is still located on the same network where
it
obtained its current lease, and continues to use the lease as long as the
lease is still valid. So, the client can interact with the network using
the
leased IP address.

Our teacher (and a lot of books) says:
If the client has a valid IP lease and the DHCP server is unavailable
during
the client restart, the client will configure an APIPA address. So, the
client interacts with the network using an APIPA address.

Please, what is the correct process?

regards
chris

That depends on the lease time. If the lease time is, say, 8 days then
you client will simply connect using its existing IP. After 50% has expired
(ie about 4 days) it will request a renewal of the lease. The DHCP will
comply if it is available.

If the lease time is only a few hours, then the client might need to get
a new IP from DHCP. In that case, failure to find the DHCP server will
result in the client configuring an APIPA address. That is the default
behavior if the client is configured to get an IP automatically but no DHCP
server is available.


.

.

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