DHCP server is giving itself a second IP

I would exclude the Static IP from the scope instead of reserving it. Then I would manually set the IP back to the excluded address and bypass DHCP altogether. Hope this helps,

Dave

caller number 6 stole my thunder. I too was going to ask about a second nic. We had a gateway server with integrated NIC ( which was turned off in BIOS ), and the primary NIC was a 3com10/100. We had an extended power outage, and the bios was reset with defaults, letting the second nic bind, causing no end of problems.

Also, any Network storage devices attached, ie Tape Drives, CD-roms, or external HD boxes?

You say:
From Rob Baugh on 12/12/00 03:46 PM EST: My DHCP server is also the PDC, DNS, Wins. Rebuilding DHCP, and any IP related protocals is not really an option right now. As far as moving to a Linux server, definatly not an option. We semi-recently moved the DHCP service to this machine, because the original DHCP server was doing the same thing. I really don't want to keep deleting and reinstalling the DHCP service.

1) Check the MAC: does it reflect the "original" machine; not the newone?
2) Or your server has been hacked; and this is a sym.

I think the MAC is a way for tracing the problem. Besides, you have not given details on your setting. Does you use NT 4.0 with SP6 or win 2000; How many PDC?

I have found that in MS knowledge base:
Automate Setup to Configure TCP/IP for Static Addressing Fails
(for NT 3.5 and 3.51)

http://support.microsoft.com/support/kb/articles/Q133/3/37.asp?LN=EN-US&SD=gn&FR=0&qry=DHCP%20does%20not%20use%20static%20IP&rnk=4&src=DHCS_MSPSS_gn_SRCH&SPR=NTS

I hope it can help you.

I was going to ask about 2nd NIC as well, and for SP version, OS, hardware environment as well. If using SP4, up to 5 or 6. Check for roll-ups or hotfixes as well. I've had no probs with SP3 or SP5 with DHCP server.

I would also concur on tracingproblem through MAC since you've already disabled DHCP client.

Good Luck.

I can sense your frustration, but please be patient while I try to get your situation straight. What do you mean when you say in your original question, "DHCP...has given itself another, dynamic, IP?" This should be impossible, which leads me to believe that TCP/IP was not properly configured on the server(especially since you said you found the same situation occuring on two different machines).

I am wondering if you have the NIC(s) on the server configured to get an IP address from a DHCPserver (in this case, itself), and then you reserved those IP addresses in DHCP manager. Because you are mentioning MAC addresses, this leads me to believe that you are viewing active leases in DHCP manager that have reservations. When you "reserve"an IP address, you are telling the DHCP server that when a particular client (in this case your DHCP server) requests an IP address, always give them this one.

When you "exclude" IP addresses, it is usually because you have static addresses on your network that fall within your scope.

When you go to Network Neighborhood -> Properties -> Protocols -> TCP/IP -> Properties, your DHCP server's NIC(or NICs) should have static addresses. If these addresses are within the scope, you should exclude them in DHCP Manger -> DHCP Options -> Scope -> Excluded Addresses.

I would try a couple different things:

1) Is there another DHCP server running somewhere? Microsoft has a tool on the NT resource kit CD called Dhcploc.exe which locates DHCP servers on a subnet. You mentioned that the DHCP was moved to another server? This may possibly be your answer. The NIC could be obtaining an IP from there from bootp.

Don't forget about hardware such as firewalls that may have built in DHCP. This is the first step I would take.

If there is only one DHCP server on the subnet, make sure it is the one you are configuring.

After that, I would attempt to use a new NIC. Make sure it is namebrand (I prefer 3Com 3C905C Series for 10/100) with the most current driver off the web. Replacing the NIC will be far less expensive than troubleshooting forever.

1. Make sure your server is not sitting on the 1st IP address in your subnet. Remember, TCP/IP reservers this address for management. Try using the 2nd or 3 address for your NIC.

2. Check the binding order. Go to the network icon in control panel, bindings tab and look to see if your NIC is at the top of the list for ALL BINDINGS AND PROTOCOLS. If you have a modem, added a second NIC, or NT sees anything it would regard as an adapter, it can throw the whole thing off.

3. Exclude the first N addresses in the scope. N = 1 for each adapter and modem + 1 for RAS + (NIC address - 1st address in scope).
EX: 2 NICS + 4 MODEMS + 1 RAS + (10.0.0.2-10.0.0.0) = 9

4. If multiple workstations are grabbing the same IP, run winipcfg or ipconfig (depending on 9X or NT) and release both offending workstations first. Then reboot both, ONE AT A TIME.

The reason why the DHCP Server might assign itself an IP address is if it is a RAS Server. Are you loosing any functionality?
Are there any error messages in the event logs?

Okay, a lot has been said and the question seems rather straight-forward and specific. Let's try to break it down into possibilities. Here are the facts:

"My DHCP server is setup with a Static IP."

Good, so far, we also know that there's only one NIC and no RAS.

"That IP is reserved for the DHCP."

You've already stated that this is an incorrect term -- the (static) IP Address is *excluded* from the scope.

"The DHCP however has set the IP to an inactive status"

Okay, I'm having trouble here. If the address is excluded, DHCP isn't keeping any record of this address. What do you mean?

"...and has given itself another, dynamic, IP."

What is the evidence to this assertion? You stated in earlier responses that the MAC address of the offending lease is different (than the server's) and that the server's static address was still ping*able*.

Are you just seeing the server's host name in an active lease? I wonder because you asked if DHCP cared about duplicate names.

(It doesn't, by the way, it just takes what it's given. NetBIOS can't handle duplicate names and TCP/IP can't handle duplicate IP addresses).

"Does anyone know why it might be doing this and how to resolve the issue?"

I'm unclear as to what the issue is. Do you have any loss of network functionality? Or, are you losing sleep because you can't wrap your head around a questionable lease?

If the answer is the latter, the following command may provide some relief:

nbtstat -A www.xxx.yyy.zzz

Note the capital letter, 'A'. Substituting the IP address of the *bad* lease for www.xxx.yyy.zzz will produce the remote machine's NetBIOS name registrations (logon username, NetBIOS computer name, Windows NT domain, and services that register NetBIOS names) and the MAC address. From this, you might better see where the machine with the duplicate host name is w.r.t. the NT domain.

I know this might sound silly and you probably have done this , but have you re-applied the service pack ?

Hope this long shot helps.

I know this might sound silly and you probably have done this , but have you re-applied the service pack ?

Hope this long shot helps.

If I were you, rather than spend any more time on trying to solve this problem, I would schedule some off-hours time, and remove all networking components from this machine and re-add them. Remove all network services, protocols, and adapters, then re-boot. Then, re-add all the networking components, including the dhcp service. This time when you set up DHCP, make sure to set up the scope so that it does not include all of the IP addresses in your subnet. You should reserve some IP addresses outside of your DHCP scope for servers and networking equipment, possibly printers also.

BTW, I do not believe this problem to be with the DHCP service. I think it is a problem with your network settings on the server or possibly the network card itself. If the above does not work, replace the network card and try again.

my hunch is that ur dhcp server's arp cache has entry for conflicting ip address
arp -a to find the prob. address if present delete it using arp -d a.b.c.d
may be this will help