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NT4 DHCP client recieves no Gateway

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by lordinfidel

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I've been researching this issue for a while and have not been able to find any MS KB articles about it.

Basically, on my LAN, I have a mixed MS OS enviroment. I have several DHCP servers (NT4 srvr) handing out leases for a /25 block. All leases are for 24 hours and contain the generic IP/Mask/Gtwy/DNS.

The problem is most of My NT4 wkstn DHCP clients are not receiving the gateway as part of their lease. This has happened in the past and is generally more prevelant right after a IP Netwk address change.

After the last change over though it has become a daily occurence and is getting quite annoying.

2K and 98 clients have not issues receiving the full lease. The NT4 clients that experience this do not share any common switch. Some come in directlty into the noc to patch panel then into a switch. Others pass from switch to noc patch panel then into switch. We have multiple switches in the noc that connects the network together.

We are not using spanning tree on the switches.

Any ideas?

(originally I've changed out adapters thinking it was the adapter, I've re-run new drops.... I've stopped trying to fix it once I realized that the machines it was happening to were all NT4 wkstn's.)

20 replies

by chinl

In DHCP make sure the global scope has the service "router" set with the value of your gateway

Couple of things may cause the problem if the above is OK.
1. Locally set gateway will negate the gateway setting from the DHCP server.
2. It may be picking up the IP from another DHCP server without the "Router" set

by lordinfidel

The scopes on both DHCP servers are correct. Of that *was* the case then All OS's on my lan receiving leases from the offending server would be incorrect.

This is not the case.

Only NT4 wkstn's are receiving incorrect leases. And they are not all being recieved from the same DHCP server. If they were coming from one server then I can say it's that server. But it is coming from both servers.

Also notable, we do not allow typical LAN traffic past the firewall. So picking up a lease from another network is not an option.

1 more thing... The IP and Mask are correct in the lease. It is just that it is not receiving the gwy. And there is no manual gateway set on the client machine.

by gperrie

Hi

An ipconfig /all at a command prompt should tell you the IP of the DHCP server the lease was received from. You could double check here to be sure which server hands out the address.

If you do a manual ipconfig /release then ipconfig /renew, does it get the correct settings?

Are all the workstations on the same SP level? Which level are they at?(I sound like Microsoft - We can't help if you haven't installed the latest SP)

Gavin

by lordinfidel

Thanx..... But I have already gone thru the basics.

They are not locked down to 1 specific dhcp server. It is a NT4 wkstn issue receiving leases in a switched enviroment.

I just don't know why.

All systems are sp6a.

by lordinfidel

I have changed the points to 2K.

*****Please Note*******

While a appreceiate the last 2 posters responses.
I am an extremely seasoned admin and have gone thru all of the basics. My counterpart at the company who is even better than I am, is unable
to figure this one out.

I am looking for any article that describes this issue. Not troubleshooting tips.

Local lan is a switched enviroment with cisco catylsts. However some machines are going thru Intel 140T hubs.

There are 2 dhcp servers, both NT4 srvr sp6a. With all hotfixes applicable to our enviroment.

This ONLY happens to NT4 wkstn clients. It does not matter where they are located in the building.
It does not matter which srvr they get the lease from.

Please, while I appreciate the attemps at helping, Please only submit Viable answers that attempt to address this issue.

Yes, I have put a sniffer on this to see what is happening.

by lordinfidel

It really never did help, but it was the more intelligent of the answers.

Since the netwk infrastructure has long been renovated, and all wkstn's/servers upgraded. This is a moot point and the question should of have been killed a 2 years ago.

It will remain a mystery.

by lordinfidel

I have not forgotten about my question and am still researching it.

I have read the cisco tac but have not had a chance to research it further.

It's way down at the bottom of the list.

When I get back to it I will award if warranted.

by shmaltz

Look up the follwing (remove spaces):
http://support.microsoft.com/default.aspx?scid=kb;en-us;167049
The above explains that NT is the only MS OS (it doesn't mention XP) that will not accept a gateway that is not on the local subnet. If your Gateway has an address that is not on the local subnet WinNT clients will not accept it.
I believe the next one doesn't apply to you, however I think that I should add it just in case someone else is researching this problem and is looking for a solution:
http://support.microsoft.com/default.aspx?scid=kb;en-us;249003
This one explains a situation where a client receives set the Gateway to the same address as the IP address, MS says it has to do with the switch.
Hope this helps.

by shmaltz

I believe if this is the problem then the only workaround would be either to setup a gateway that is local, or to add a gateway using the Route command with if.

by lordinfidel

Thx, I had already looked at that one. But it did not apply because all systems are local and the gtwy is a local address.

by haruss

I went bqack to a book that I have in my library, Since DHCP is a broadcast not all ruters (unless they are RFC-1542 compliant) will forward DHCP packets. The books solution was three fold. Install DHCP srever on each subnet. (too expensive) Install RFC-1542 routers, (also too expensive. Add a DHCP relay service on a WIN NT box on the subnet. May help. Also the book states that Windows NT uses DNS server addresses that is entered on the DNS page in Microsoft TCP/IP properties.

Why not add a default gateway to the workstations and not beat yor head on the ground? Just a suggestion..

by lordinfidel

All routers are rfc-1542 compliant, (we are a cisco shop). DHCP does not traverse the routers anyways.

The same wkstn can be plugged directly into the same switch that the dhcp srvr is on, and still not get the gtwy.

Your right, why not just assign a dflt gtwy to the wkstns. I did do that already.

It's just I have been living with this for the last couple of years. And I really dislike unsolved mysteries. Myself and 2 other admins at the company have looked at this and do not have an answer. Nor does anywone I ask.

I was hoping that someone, somewhere, has experienced the same behaviour that I am seeing.

by Member 30543440

Well, for NT Workstaions You might need to have WINS Servers, as well, to support Netbios names, .e.g

then, in a DHCP, You should describe WINS/NBNS Servers and WINS?NBT Node Types.

Thanks
David
P.S. Hope, it is not from another story ;-)

by lordinfidel

thanx for the comments david.

In this scenario, wins does not play a factor.

Wins helps in cutting down netbios name resolution broadcasts. But what I am talking about is the wkstn receiving and registering all dhcp options expect for the default gateway.

It does not make any sense and like I said before, it has remained a mystery on my network for the past few years and will probably remain until I get rid of the last DHCP enabled NT4 machine.

by paulo.sedrez

I read about something about NT4 DHCP server, I don't remember where: the server will only send the parameters requested by the client, not all parameters as other DHCP servers do.

So, check HKEY_LOCAL_MACHINE\Software\Microsoft\Tcpip for leftover gateway parameter (even all zeros).

Also (but I'm sure you checked this first) see that the default gateway is the 3 (ROUTER) DHCP parameter, and not 33 (GATEWAY or STATIC ROUTES). Just for sanity check.

--Sedrez

by lordinfidel

I appreciate the comments, but this question is dead.

This only occured in specific NT4 clients, regardless of the dhcp server they were being directed to. Meaning it was not global.

The netwk infrastructure has long been upgraded as well as all server's and wkstn's. This issue no longer exists and shall remain a mystery.

by kevin.stace

release and renew the NT4 wkst IP's with ipconfig /release and /renew, you will now notice that they have gateway connectivity.Your W2K & 98 wkst are unaffected as they have what is an inprovement on DHCP called "automatic client configuration" which automativaly renews the lease for the IP address given to the w2k or 98 clients when a connection is made with the DHCP server. A feature unavailable in DHCP client side with NT4 (hope this solves the mystery, still need to find a solution for NT4)

by lordinfidel

This was tried. But if it was true then this would be a more wide spread issue thru all networks (not just on mine) and the issue documented someplace. Basically it occured from only a few wkstn's (in a +1K user enviroment), and it did not matter which NT4 dhcp server it was getting the lease from.

Nor were they coming from the same vlan.

I appreciate the comments, but this question is dead, I apologize for not killing it earlier.

The netwk infrastructure has long been upgraded as well as all server's and wkstn's. This issue no longer exists and shall remain a mystery.

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