DHCP server not responding

We have DHCP running on a Windows 2000 server. Other than servring the local
office, it also serves several remote offices over the WAN via DHCP relay.
Everything works fine. Recently, we are required to serve another remote
office. For some reasons, the DHCP server does not respond to any requests
from this remote office.
I have used the Microsoft Network Monitor to capture some network traffic,
which shows that the DHCP server does receive DHCP requests (Discover and
Request) from the new office but for some reasons, it does not send an Ack
back. The new scope is set up exactly the same way as the other offices.
The routers at both ends are also configured the same way as for the other
remote offices. There is no error message in the event log.
The only difference between between this remote office and others is that it
does not have the whole subnet, i.e., its netmask is 255.255.255.128 while
all others have 255.255.255.0... I am not sure if this matters.
Anyway, I am stuck. Any help?
Thx.

Hello helpwanted,

Any firewall option blocking the traffice on the router between them?

Best regards

Meinolf Weber
Disclaimer: This posting is provided "AS IS" with no warranties, and confers
no rights.
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> We have DHCP running on a Windows 2000 server. Other than servring
> the local
> office, it also serves several remote offices over the WAN via DHCP
> relay.
> Everything works fine. Recently, we are required to serve another
> remote
> office. For some reasons, the DHCP server does not respond to any
> requests
> from this remote office.
> I have used the Microsoft Network Monitor to capture some network
> traffic,
> which shows that the DHCP server does receive DHCP requests (Discover
> and
> Request) from the new office but for some reasons, it does not send an
> Ack
> back. The new scope is set up exactly the same way as the other
> offices.
> The routers at both ends are also configured the same way as for the
> other
> remote offices. There is no error message in the event log.
> The only difference between between this remote office and others is
> that it
> does not have the whole subnet, i.e., its netmask is 255.255.255.128
> while
> all others have 255.255.255.0... I am not sure if this matters.
> Anyway, I am stuck. Any help?
> Thx.

"helpwanted" <> wrote in message
news:6A80D9DF-8998-451C-908A-...
> We have DHCP running on a Windows 2000 server. Other than servring the
> local
> office, it also serves several remote offices over the WAN via DHCP relay.
> Everything works fine. Recently, we are required to serve another remote
> office. For some reasons, the DHCP server does not respond to any
> requests
> from this remote office.
> I have used the Microsoft Network Monitor to capture some network traffic,
> which shows that the DHCP server does receive DHCP requests (Discover and
> Request) from the new office but for some reasons, it does not send an Ack
> back. The new scope is set up exactly the same way as the other offices.
> The routers at both ends are also configured the same way as for the other
> remote offices. There is no error message in the event log.
> The only difference between between this remote office and others is that
> it
> does not have the whole subnet, i.e., its netmask is 255.255.255.128 while
> all others have 255.255.255.0... I am not sure if this matters.
> Anyway, I am stuck. Any help?
> Thx.


I agree with Meinolf in his questioning concerning a possible firewall
blocking traffic. Otherwise you would have seen some sort of traffic coming
across in your capture.

I wouldn't think the subnet matters, as long as you've configured the scope
with that subnet and setup the agent properly to listen to requests, and of
course the DHCP server is set properly in the agent, and it can communicate
to the DHCP server with not firewall blocks.

--
Ace

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Please reply back to the newsgroup or forum to benefit from collaboration
among responding engineers, and to help others benefit from your resolution.

Ace Fekay, MCT, MCTS Exchange, MCSE, MCSA 2003 & 2000, MCSA Messaging
Microsoft Certified Trainer

For urgent issues, please contact Microsoft PSS directly. Please check
http://support.microsoft.com for regional support phone numbers.

No firewall options in between just like the routers for the other remote
offices.
When creating the new scope, I simply cloned from the other existing scopes
which are working very well. Is there any log files I should check...
basically any other ideas?
Thx.

"Ace Fekay [MCT]" wrote:

> "helpwanted" <> wrote in message
> news:6A80D9DF-8998-451C-908A-...
> > We have DHCP running on a Windows 2000 server. Other than servring the
> > local
> > office, it also serves several remote offices over the WAN via DHCP relay.
> > Everything works fine. Recently, we are required to serve another remote
> > office. For some reasons, the DHCP server does not respond to any
> > requests
> > from this remote office.
> > I have used the Microsoft Network Monitor to capture some network traffic,
> > which shows that the DHCP server does receive DHCP requests (Discover and
> > Request) from the new office but for some reasons, it does not send an Ack
> > back. The new scope is set up exactly the same way as the other offices.
> > The routers at both ends are also configured the same way as for the other
> > remote offices. There is no error message in the event log.
> > The only difference between between this remote office and others is that
> > it
> > does not have the whole subnet, i.e., its netmask is 255.255.255.128 while
> > all others have 255.255.255.0... I am not sure if this matters.
> > Anyway, I am stuck. Any help?
> > Thx.
>
>
> I agree with Meinolf in his questioning concerning a possible firewall
> blocking traffic. Otherwise you would have seen some sort of traffic coming
> across in your capture.
>
> I wouldn't think the subnet matters, as long as you've configured the scope
> with that subnet and setup the agent properly to listen to requests, and of
> course the DHCP server is set properly in the agent, and it can communicate
> to the DHCP server with not firewall blocks.
>
> --
> Ace
>
> This posting is provided "AS-IS" with no warranties or guarantees and
> confers no rights.
>
> Please reply back to the newsgroup or forum to benefit from collaboration
> among responding engineers, and to help others benefit from your resolution.
>
> Ace Fekay, MCT, MCTS Exchange, MCSE, MCSA 2003 & 2000, MCSA Messaging
> Microsoft Certified Trainer
>
> For urgent issues, please contact Microsoft PSS directly. Please check
> http://support.microsoft.com for regional support phone numbers.
>
>
>
>

"helpwanted" <> wrote in message
news:C71D014D-3736-4B8F-9047-...
> No firewall options in between just like the routers for the other remote
> offices.
> When creating the new scope, I simply cloned from the other existing
> scopes
> which are working very well. Is there any log files I should check...
> basically any other ideas?
> Thx.
>
>

Cloned? I assume you mean you manually created the scope mimicking the other
scope settings and didn't use a tool to clone it.

How many interfaces are on the DHCP server? I assume in your captures that
if there are more than one interface, you've checked to make sure the ACKs
weren't being sent over a different interface.

As for monitoring, read the following. Let us know what you find.

How to Monitor the DHCP Log FileThis article describes how you can monitor
only certain events from the Dynamic Host Configuration Protocol (DHCP) log
file in Microsoft Operations Manager ...
http://support.microsoft.com/kb/298367

Changes in Windows Server 2003 DHCP LoggingApr 7, 2003 ... This article
describes the changes in Dynamic Host Configuration Protocol (DHCP) server
logging in Windows Server 2003.
http://support.microsoft.com/kb/328891

Ace

There is only one network interface in our server.

We don't run MOM in our office.

I looked more closely at the network traffic captured by Network Monitor. I
noticed that when the server receives the Discover packet from the new
office, it doesn't respond at all. But for all other offices, it responds
with an Offer packet as expected (and then a Request packet and then an Ack).

I am assuming even if the routers/switches discards the Offer packets, it
should still show up in Network Monitor.

When I check the DHCP log file, it doesn't even have anything reported about
the Discover packet from the new office.

Any help is very much appreciated?


"Ace Fekay [MCT]" wrote:

> "helpwanted" <> wrote in message
> news:C71D014D-3736-4B8F-9047-...
> > No firewall options in between just like the routers for the other remote
> > offices.
> > When creating the new scope, I simply cloned from the other existing
> > scopes
> > which are working very well. Is there any log files I should check...
> > basically any other ideas?
> > Thx.
> >
> >
>
> Cloned? I assume you mean you manually created the scope mimicking the other
> scope settings and didn't use a tool to clone it.
>
> How many interfaces are on the DHCP server? I assume in your captures that
> if there are more than one interface, you've checked to make sure the ACKs
> weren't being sent over a different interface.
>
> As for monitoring, read the following. Let us know what you find.
>
> How to Monitor the DHCP Log FileThis article describes how you can monitor
> only certain events from the Dynamic Host Configuration Protocol (DHCP) log
> file in Microsoft Operations Manager ...
> http://support.microsoft.com/kb/298367
>
> Changes in Windows Server 2003 DHCP LoggingApr 7, 2003 ... This article
> describes the changes in Dynamic Host Configuration Protocol (DHCP) server
> logging in Windows Server 2003.
> http://support.microsoft.com/kb/328891
>
> Ace
>
>

"helpwanted" <> wrote in message
news:527A51B6-8567-4885-83F4-...
> There is only one network interface in our server.
>
> We don't run MOM in our office.
>
> I looked more closely at the network traffic captured by Network Monitor.
> I
> noticed that when the server receives the Discover packet from the new
> office, it doesn't respond at all. But for all other offices, it responds
> with an Offer packet as expected (and then a Request packet and then an
> Ack).
>
> I am assuming even if the routers/switches discards the Offer packets, it
> should still show up in Network Monitor.
>
> When I check the DHCP log file, it doesn't even have anything reported
> about
> the Discover packet from the new office.
>
> Any help is very much appreciated?
>
>

Interesting. You're saying the captures indicate the Discover packet is
reaching the server, so that verifies it's getting to the server, yet the
DHCP logs don't even show it showing up? I believe I remember you saying
there is no subnet mask or subnet ID mismatch for the scope and the subnet
(the /25)?

Try creating the scope as a /24, but exclude the range that;s not included
wtih the /25 at the office, just for a test to see if it works. What the
difference changing it at this point, since it's not working anyway?

Ace

IT WORKS! looks like dhcp doesn't know how to handle subnet mask. What is
the point of entering the subnet mask when creating the scope!

THANK YOU VERY MUCH FOR YOUR HELP...

"Ace Fekay [MCT]" wrote:

> "helpwanted" <> wrote in message
> news:527A51B6-8567-4885-83F4-...
> > There is only one network interface in our server.
> >
> > We don't run MOM in our office.
> >
> > I looked more closely at the network traffic captured by Network Monitor.
> > I
> > noticed that when the server receives the Discover packet from the new
> > office, it doesn't respond at all. But for all other offices, it responds
> > with an Offer packet as expected (and then a Request packet and then an
> > Ack).
> >
> > I am assuming even if the routers/switches discards the Offer packets, it
> > should still show up in Network Monitor.
> >
> > When I check the DHCP log file, it doesn't even have anything reported
> > about
> > the Discover packet from the new office.
> >
> > Any help is very much appreciated?
> >
> >
>
> Interesting. You're saying the captures indicate the Discover packet is
> reaching the server, so that verifies it's getting to the server, yet the
> DHCP logs don't even show it showing up? I believe I remember you saying
> there is no subnet mask or subnet ID mismatch for the scope and the subnet
> (the /25)?
>
> Try creating the scope as a /24, but exclude the range that;s not included
> wtih the /25 at the office, just for a test to see if it works. What the
> difference changing it at this point, since it's not working anyway?
>
> Ace
>
>
>

"helpwanted" <> wrote in message
news:538A8969-D6D5-4FCD-BB4E-...
> IT WORKS! looks like dhcp doesn't know how to handle subnet mask. What
> is
> the point of entering the subnet mask when creating the scope!
>
> THANK YOU VERY MUCH FOR YOUR HELP...

No kidding... Wow. I can't explain it. I haven't had problems with subnet
masks in a non-agent scenario, such as a small or medium office using a /27,
etc, but for an agent... hmm.

Oh well, glad it's working! And you're welcome!

Just make sure you use exclusions for the IPs that are not on that net.

Cheers!

Ace