OK, in this case I'll recommend trying the monitoring solution: use Network
Monitor from the Windows distro, or any other sniffer tools. Try capturing
packets from the network, first plug the capturing station directly to the
hub that is attached to the server, and see if the server responds with the
correct subnet mask in DHCP_OFFER and DHCP_ACK packets.
If that is still the server which issues bad packets, then we might research
this issue further as we have located its source.
--
Dmitry Korolyov [(E-Mail Removed)]
MVP: Windows Server - Directory Services
"J3r3myS" <(E-Mail Removed)> wrote in message
news:2C563662-F314-4CBC-98EC-(E-Mail Removed)...
> Dmitry,
>
> There is a chance that my Dell Powerconnect 3024 Switches are causing a
> problem but: I have been using the switches for over a year without this
> problem, I just upgraded the firmware to the newest version to try to fix
> the
> problem. Also,
>
> I tried your suggestion: I plugged in some computers that were having the
> problem into a hub that the DHCP server was also plugged into. When the
> clients renewed their leases they get the same subnet mask of 255.0.0.0.
>
> "Dmitry Korolyov [MVP]" wrote:
>
>> Is there any chance that your network equipment ("smart" switches and so
>> on)
>> "patches" the DHCP packets with different subnet mask? You know, 10.x.x.x
>> is
>> typically used with /8 instead of /24. So I wouldn't drop that chance.
>> Try
>> establishing some sort of relationship between your network topology and
>> clients which get incorrect subnet mask; maybe it's the hardware that
>> causes
>> problem.
>>
>> Also, try plugging 2-3 of the clients which get incorrect mask into a
>> simple
>> old-styled hub and connect it to the DHCP server directly, and see if
>> they
>> will still get the incorrect mask.
>>
>> You can also use sniffer on different network segments between DHCP
>> server
>> and your clients to see if its DHCP server itself issuing packets with
>> incorrect subnet mask, or this change happens somewhere while the packet
>> is
>> on its way from the server to the client.
>>
>> --
>> Dmitry Korolyov [(E-Mail Removed)]
>> MVP: Windows Server - Directory Services
>>
>>
>> "J3r3myS" <(E-Mail Removed)> wrote in message
>> news:9A6BD21C-5C3D-41D9-9DDB-(E-Mail Removed)...
>> >I have win2k3 domain controller with DHCP Service. About 100 clients,
>> >mostly
>> > winxpPro, a few win2k. No problems for over a year. Using one scope,
>> > 10.10.10.1 - 10.10.10.254. The subnetmask is 255.255.255.0 I have some
>> > exclusions and reservations.
>> >
>> > The scope options are:
>> > Router
>> > Time Server
>> > DNS Servers
>> > NDS Domain Name
>> > Wins Servers
>> > WIns Node Type - H node
>> >
>> > 2 months ago random clients began to get the wrong subnetmask. They had
>> > 255.0.0.0 as the subnetmask. Ipconfig /all showed everything correct
>> > including the dhcp server except for the subnetmask. If I release and
>> > renew
>> > the ip, I get the correct subnetmask. Now almost all of the clients
>> > have
>> > the
>> > incorrect subnetmask.
>> >
>> > I have removed the dhcp server and verified that clients were not
>> > receiving
>> > ip info from another DHCP server. I have moved the DHCP service to
>> > another
>> > server. I have moved the DHCP service back to the PDC and re-entered
>> > all
>> > dhcp
>> > config manually. I also upgraded the firmware in all switches.
>> >
>> > I have run out of ideas. Any suggestions?
>> >
>> > Thanks.
>> >
>> >
>>
>>
>>
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