DHCP - obscure error message

T

Terry Pinnell

In Event Viewer I see many errors like this
---------
DHCP
"The IP address lease 192.168.x.xx for the Network Card with network
address xxxxxxxxxx has been denied by the DHCP server 192.168.1.1 (The
DHCP Server sent a DHCPNACK message)." [I've inserted the x's for
security.]
 
W

Whiskers

["Followup-To:" header set to 24hoursupport.helpdesk.]
In Event Viewer I see many errors like this
---------
DHCP
"The IP address lease 192.168.x.xx for the Network Card with network
address xxxxxxxxxx has been denied by the DHCP server 192.168.1.1 (The
DHCP Server sent a DHCPNACK message)." [I've inserted the x's for
security.]


<http://www.ex-designz.net/tcpipguide.asp>:-

LEASE RENEWAL
DHCP clients will attempt to renew their leases when %50 of the lease
has expired. The client will send a DHCPREQUEST message to the server
that assigned the lease. Assuming the DHCP server isn't on fire or
anything it will send out a DHCPACK with the new lease. If the server
is unavailable, then the client can continue functioning as it has %50
remaining still. The client will continue as normal until the lease
reaches %87.5 used at which time it broadcast to all DHCP servers and
attempt to get a new lease. If the client receives a DHCPNACK message
or the lease expires then the client must start all over again and will
get a different IP address. If the lease expires and the client is
unable to get a new one then the user will be whining to their IS dept.
about it because they will not be able to communicate over the network.


See also
<http://www.microsoft.com/technet/support/ee/SearchResults.aspx?Type=0&Message=dhcpnack>
 
G

Gerry

You're the cat's whiskers <G>. When I saw Terry's question I did not
expect such an formative reply!



~~~~


Gerry
~~~~
FCA
Stourport, England
Enquire, plan and execute
~~~~~~~~~~~~~~~~~~~
Whiskers said:
["Followup-To:" header set to 24hoursupport.helpdesk.]
In Event Viewer I see many errors like this
---------
DHCP
"The IP address lease 192.168.x.xx for the Network Card with network
address xxxxxxxxxx has been denied by the DHCP server 192.168.1.1
(The DHCP Server sent a DHCPNACK message)." [I've inserted the x's
for security.]


<http://www.ex-designz.net/tcpipguide.asp>:-

LEASE RENEWAL
DHCP clients will attempt to renew their leases when %50 of the
lease has expired. The client will send a DHCPREQUEST message to
the server that assigned the lease. Assuming the DHCP server
isn't on fire or anything it will send out a DHCPACK with the new
lease. If the server is unavailable, then the client can continue
functioning as it has %50 remaining still. The client will
continue as normal until the lease reaches %87.5 used at which
time it broadcast to all DHCP servers and attempt to get a new
lease. If the client receives a DHCPNACK message or the lease
expires then the client must start all over again and will get a
different IP address. If the lease expires and the client is
unable to get a new one then the user will be whining to their IS
dept. about it because they will not be able to communicate over the
network.


See also
<http://www.microsoft.com/technet/support/ee/SearchResults.aspx?Type=0&Message=dhcpnack>
 
J

John Wunderlich

In Event Viewer I see many errors like this
---------
DHCP
"The IP address lease 192.168.x.xx for the Network Card with
network address xxxxxxxxxx has been denied by the DHCP server
192.168.1.1 (The DHCP Server sent a DHCPNACK message)." [I've
inserted the x's for security.]

Is this a laptop that often moves from one network to another?
When contacting a DHCP server for an IP address, the computer usually
expresses a preference for the last IP address that it had. If the
DHCP server determines that that IP address is currently unavailable
or that the requested address does not belong to the subnet served by
the DHCP server, then you will log the error that you cite in the
Event Viewer. This is perfectly normal and simply indicates that the
"quick" DHCP assignment failed and that the regular DHCP assignment
process is being forced.

HTH,
John
 
T

Terry Pinnell

John Wunderlich said:
In Event Viewer I see many errors like this
---------
DHCP
"The IP address lease 192.168.x.xx for the Network Card with
network address xxxxxxxxxx has been denied by the DHCP server
192.168.1.1 (The DHCP Server sent a DHCPNACK message)." [I've
inserted the x's for security.]

Is this a laptop that often moves from one network to another?
When contacting a DHCP server for an IP address, the computer usually
expresses a preference for the last IP address that it had. If the
DHCP server determines that that IP address is currently unavailable
or that the requested address does not belong to the subnet served by
the DHCP server, then you will log the error that you cite in the
Event Viewer. This is perfectly normal and simply indicates that the
"quick" DHCP assignment failed and that the regular DHCP assignment
process is being forced.

HTH,
John

Thanks John. This is just a WinXP desktop PC, and I'm the sole user.
The only 'network' is my BT Broadband connection and a cable
connecting my old PC to my router temporarily, to allow copying of
files. What and where is 'the DHCP server' that makes these choices
please?

Must say I do find this stuff very hard going! But if I've got the
drift of what you're saying, then it sounds like I don't need to
worry? Some 'lease' or other is not about to come to a sudden halt,
excommunicating me (literally) from the Net?
 
J

John Wunderlich

John Wunderlich said:
In Event Viewer I see many errors like this
---------
DHCP
"The IP address lease 192.168.x.xx for the Network Card with
network address xxxxxxxxxx has been denied by the DHCP server
192.168.1.1 (The DHCP Server sent a DHCPNACK message)." [I've
inserted the x's for security.]

Is this a laptop that often moves from one network to another?
When contacting a DHCP server for an IP address, the computer
usually expresses a preference for the last IP address that it
had. If the DHCP server determines that that IP address is
currently unavailable or that the requested address does not
belong to the subnet served by the DHCP server, then you will log
the error that you cite in the Event Viewer. This is perfectly
normal and simply indicates that the "quick" DHCP assignment
failed and that the regular DHCP assignment process is being
forced.

HTH,
John

Thanks John. This is just a WinXP desktop PC, and I'm the sole
user. The only 'network' is my BT Broadband connection and a cable
connecting my old PC to my router temporarily, to allow copying of
files. What and where is 'the DHCP server' that makes these
choices please?

Must say I do find this stuff very hard going! But if I've got the
drift of what you're saying, then it sounds like I don't need to
worry? Some 'lease' or other is not about to come to a sudden
halt, excommunicating me (literally) from the Net?

The DHCP Server is the program that assigns you your IP address when
you connect to the network. If you connect directly to your
Broadband connection, the DHCP server is managed by your ISP. If you
connect to a router, then the router provides the DHCP function.
Connecting to a router, you usually get an IP address like
192.168.x.x. Connecting to your broadband, you would get a different
IP address. When your computer asks the DHCP server for an IP
address, it usually tries to take a shortcut by saying something like
"I need an IP address and, by the way, I'd prefer the last IP address
I had which was X.X.X.X" It would not be unusual for the DHCP server
to reply saying "I'm sorry but X.X.X.X is not currently available".
When this happens, you get the message that you see in your Event Log
and your computer will ask again for an IP address but this time it
will not express a preference.

When assigned an IP address via DHCP, there will be a time limit on
the use of this IP address. This is the "lease" time. Routers will
usually default to about a week, and ISPs will default anywhere
between a couple of hours to a couple of days. You can see your
lease expiration by bringing up a command window (start->run->cmd)
and entering the command: ipconfig /all
When the lease is half-over, your computer will automatically attempt
to renew the lease. It is rare for a lease not to renew; however,
should it not renew before it expires, yes you will be (as you put
it) excommunicated from the network. The main reason for the lease
is that should you drop off the network without formally releasing an
IP address, that IP address will eventually automatically expire and
revert back into the pool for assignment to another user.

HTH,
John
 

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