NT - DHCP Server

[datadan]

I have just setup an NT4.0 (sp6a) DHCP server.

A couple of questions:

1) When viewing active leases I only see a hardware address, computer name, IP, and client comments. I believe the hardware address is the NIC card of the client computer. The name is the clien computer identification. However, what do I configure to get a value in the client comments field?

2) Can I use DHCP to turn IPX routing off on the client, forcing it to use TCP/IP only?

3) I have a DHCP and one client (That I know of) setup on the network. Yet when I look at active leases I see the first address and the second used. The second is my client computer. I don't recognize the hardware address of the first. Does the DHCP server take up an additional IP even though its static?

4) How do I prevent just anyone from plugging into my network and getting a lease?

5) Can my one DHCP server hold DHCP assigmnent for mulitple domains, even though the server itself may be on a different domain than the computers requesting IP addresses?

6) Traffic: I don't have a sniffer and therefore cannot monitor traffic. Are there any gotchas I need to be aware of in terms of increase traffic when migrating from Static to DHCP?

Thanks,

 

[chronos1]

Hi datadan, i've only got some of the answers - hope they're useful,

1) Client comments field in DHCP are for reserved leases only. In DHCP Manager, go to Scope, Add Reservations - you can then specify a reserved IP address and put in any comments you want.

2) Not that i know of - if the clients are using IPX - they shouldn't be able to connect to your NT server, unless you install TCP on them, or GSNW (or something similar) on the server - but please check this as i'm not 100%.

3) Don't know this - but on my DHCP test server - you're right it shows another IP address, and mine's not connected to anything.

4) As far as i know, unless their machine has been added to your network - i.e. using the administrator permissions - they will not be able to get access to your network. So on this basis i do not believe they get get an IP address from your server.

5) As i understand it, if you are going to have multiple domains, you'll have to set up trusts between your domains, but within each domain you'll have to have a DHCP server. All these DHCP servers can be configured to see each other - but i think that's about it - you can't have a DHCP server from one domain providing IP leases to wrktns in another domain.

6) Don't know, sorry.

Hope this helps.

Good luck

 

[datadan]

Thanks for the information.

 

[Griffyn]

Hi there,

I'm pretty sure chronos is incorrect regarding question 4 and 5.

DHCP is quite separate from NT authentication. NT's DHCP server will not care who is asking for an IP address - it will assign one if it can.

I'll explain the process of DHCP:

1. Client PC is configured to find a DHCP server. On bootup, or whenever it is told to renew it's IP address, it sends a broadcast packet. Broadcast packets are visible to every computer on the same subnet. Routers by default will not pass them on, but can be configured to do so, so that a DHCP server on a different subnet can be used to provide IP leases. This is typically not a good way of setting things up though, and you would want a DHCP server on each subnet.

2. If a DHCP server sees the broadcast it will negotiate with the client to determine if it's current IP is valid, etc. and updates itself with the client's IP. The client then knows it can use the IP address supplied by the DHCP server. The DHCP server will also pass on other information, such as the DNS servers, gateway, etc.

In terms of traffic - broadcasts are not something you want a lot of, as they defeat the benefits of having switches on your LAN. But once the IP address has been leased, there is no additional traffic until the lease expires or is renewed.

Hope that helps,

Daryl

 

[chronos1]

Sorry datadan,

what Griffyn said sounds correct - i think i got mixed up between domains and subnets.

Apologies.

 

[datadan]

That makes sense.

Good information.

One last question. Now that I am leasing and creating reservations, where can I get a report of all IPs and computer names tied to them?

Thanks,