unable to pick up an address

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I know have my <home domain> in use. For some reason, one (out of the 2) clients will not pick up an IP and therefore unable to join the domain.
Nic and cable OK- it picks an address up if i plug it in to my ADSL router with DHCP enabled but not the hub connected to my isolated domain network.

Any ideas?

Si

 

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Si,

where is the dhcp server? is it the ADSL Modem, or your server?

Its just that you mention your domain being isolated.

 

Si,

Sorry, i didn't make myself clear. I have an <isolated> domain. This consists of 2 domain controllers and two client machines all connected to each other via a Netgear hub. The domain controller is running DHCP and DNS.
The ADSL router is only for my day to day machine which has DHCP enabled and not connected to the domain.

Si

 

Si

You say its a hub - have you checked its not plugged into the uplink port?

Also, you might like to try switching ports on the hub - you may have a duff one

 

Zeb,

yeah, checked that thanks. The port it is in works fine with the other machine. Strange isn't it...

 

even though the cable was picking up an IP from the DSL box, i decided to swop and it works.

On looking closer at the cable it is a crossover. So the zyxel dsl box was able to swop the <crossed> wires over whereas the hub couldn't.

The reason i didn't think it was a crossover was because because it was one i made and could have swarn (literally) it was a straight ...

Si

 

And another lesson learnt

 

I always mark my cross-over cables with a large amount of red tape at each end.

I started doing that after a similar mistake!

Harry.

 

Oh, good. I don't feel as silly now!

Si

 

Boyce,

For the computer that doesn't receive IP configuration from the DHCP server, does it have a machine account in Active Directory?

 

r.h. lee,

yes it did, but the crossover cable was the problem in this case.

Whilst on the subject, is there anything in place so it wouldn't have picked up an address? Some places have an ethernet socket in a cupboard for example, so what is stopping someone creeping in and picking up an address?

regards

Si

 

that is supprising. I thought there might be a <mac lock> possibly.

Si

 

Well with Windows DHCP servers you can set 'reservations' which will look at the MAC address and always lease the same IP address to that node. However, in most LAN the DHCP server will offer a lease to any node that broadcasts a discover packet.

If you want to lock down your LAN, it's best not to use DHCP.

 

Pete,

thanks for the info.

even though the data is travelling around the LAN unencrypted, to access resources you would have to authenticate, and couldn't use the web due to the proxy so it is safe as it can be i suppose...

Si

 

Sparky,

Great link, thanks.

Si

 

That solution would prevent someone from accessing the Internet but they would still get an IP address, only the gateway or other info in the class id would be different. Hence they would still potentially have conectivity to any box on the same subnet.