Problems with setting up a DHCP server :(

[latrosicarius]

Hello,

I have some problems setting up this DHCP server. I did the Add DHCP role on Windows Server 2003 according to this tutorial, it was pretty straight forward, except it doesn't work.

It's acting very strange... for instance, take a look at the following Pics:

1.) When I "Manage DHCP Servers" it takes me to this screen where it says "Not Connected" :/


2.) I click on the DHCP and it expands down and shows me my server, and it says "Active"


3.) Then I go back to the top and it says "Running" where it used to say "Not Connected" a second ago o.O


Okay, well that's all fine and dandy, but it still doesn't work. It doesn't change the IP addresses to the range that I told it to do (10.0.0.100 to 10.0.0.200) Check this out from one of my client PCs:


That's weird, huh? I've even tried rebooting both the server & the client. I checked the event logs... The server's event logs says that DHCP is ready and started, and the client's event log gives a whole lot of NtpClient and DsnApi warnings/errors, that there is no DSN server or that the DSN server doesn't support dynamic updates

Please help if you can. Thanks,

BTW, I can still log on to the server and access the Internet.

[GDVS]

At a guess you haven't disabled DHCP on your router and it's replying faster.

The way DHCP works is your computer sends out a broadcast packet saying "Anyone out there who give me an IP address?" which is known as the DISCOVER. All DHCP servers that received the packet will reply with an OFFER broadcast packet with an IP address and whatever else you set (gateway etc). The computer then picks one (usually the first it gets) and sends a REQUEST broadcast packet saying "I'd like this one please" and the server responds with an ACKNOWLEDGE broadcast packet saying "Ok, this is now yours".

Because it's all broadcast traffic you can't specify a DHCP server to use so you need to disable any other DHCP server on the network in order to test the one you set up.

As for the NTP warnings, that's a time server thing and the DSN(DNS I guess) problems are because you haven't set up the DNS service on the 2k3 server yet.

[latrosicarius]

GDVS, thanks for the reply. I've already setup the DSN server, but I guess that NTP thing as a whole different issue. I didn't know it was about the time server.

Anywho, about the DHCP, I tried disabling it in the router and releasing / renewing the client IP, but the server's DHCP did not take over, and I had to go to a different client and turn back on the router's DHCP in order to connect back to the internet.

I think the problem is with the server's DHCP itself. I will uninstall the role, and reinstall it, taking screenshots every step of the way. Please tell me if I'm doing something wrong.

[latrosicarius]

Wait, I have a question before I re-setup the DHCP role...

When combining DNS and DHCP together on one server, should I have make the server's IP address static in TCP/IP Properties, or leave it to "obtain IP address automatically", and then set the DHCP role to reserve an IP for the server?

Thanks!

[Moby-Dick]

have you authorised the server ?

try doing an ipconfig /all and it should show you where its getting DHCP info from.

also its worth noting that your servers IP isn't on the same subnet as the DHCP scope you are trying to assign clients. This isn't going to help matters much

[Moby-Dick]

Wait, I have a question before I re-setup the DHCP role...

When combining DNS and DHCP together on one server, should I have make the server's IP address static in TCP/IP Properties, or leave it to "obtain IP address automatically", and then set the DHCP role to reserve an IP for the server?

Thanks!

set the servers IP address to a static one.

[latrosicarius]

Thanks

[latrosicarius]

have you authorised the server ?

try doing an ipconfig /all and it should show you where its getting DHCP info from.

also its worth noting that your servers IP isn't on the same subnet as the DHCP scope you are trying to assign clients. This isn't going to help matters much

Oh okay I see what you mean.... I thought that the server's IP address was kinda "above and beyond" the Scope of client IP addresses. I'll change it in TCP/IP properties so it's inside the scope (like 10.0.0.100), and make it reserved in the DHCP scope.

Thanks

[latrosicarius]

One other last question:

When setting up the Default Gateway, should I leave the IP for the router blank, or enter 192.168.0.1, or assign it something different like this screenshot depicts:


Probably if I don't leave it blank, I'd have to go into the router and do something with this:

[Paul Adams]

Here's how I would configure it:

Router
IP address 192.168.0.1
Subnet mask 255.255.255.0
DHCP Server disabled

Windows 2003 Server (DC)
TCP/IP settings:
- IP address 192.168.0.2
- Subnet mask 255.255.255.0
- Default gateway 192.168.0.1
- DNS server 192.168.0.2

DHCP Server (enabled and authorised) settings:
Scope [192.168.0.x]:
- Start IP address: 192.168.0.100
- End IP address: 192.168.0.199
Server Options:
-- Router: 192.168.0.1
-- DNS Servers: 192.168.0.2

DNS Server settings:
- Forwarders tab, enter the IP address 192.168.0.1, remember to click Add

Clients
TCP/IP settings
- Obtain an IP address automatically
- Obtain DNS server address automatically


Everything has to reside in the same subnet, so any static IP you use or DHCP scope must be 192.168.0.x (in this example).
Don't put the server's IP into the scope, even as a reservation - keep the scope exclusive and out of the way - if you follow the above then you know addresses ending in 1xx are assigned by DHCP.

This should give you a working setup, where clients get an IP address in the range 192.168.0.100-192.168.0.199 and use the DC for name resolution, but any network traffic destined for the Internet is sent via the router at 192.168.0.1.

If the DC isn't able to resolve a DNS query a client sends it, then it fowards it to the router and is resolved via your ISP, then the result is given back to the client.
The clients only use the internal DNS server.

Clients should then find they can register in DNS dynamically and get time via the domain.

The command "ipconfig /all" gives a bit more information than you see by default.

If a client has IP settings that don't appear to have come from the server then it may hang onto it until the lease expires - force a release with "ipconfig /release" and try to obtain a new one with "ipconfig /renew".

[latrosicarius]

w00t! Thanks, I got it working!

The problem was (1) I originally didn't realize that the router and/or server had to reside on the same scope, and (2) I had the router's DHCP function turned on so that it would intercept all client requests for IPs, and the Windows DHCP server role would never get any connections.

Everyone here is so smart... sorry for bothering you guys lately, but thanks so much for your help!

[Paul Adams]

...I originally didn't realize that the router and/or server had to reside on the same scope...

Careful on the use of the word "scope", I think you have the right thing in mind, but subnet != scope.

A subnet, or "network" as some call it (though I dislike that as I use it to refer to the physical interconnection of the machines, possibly spanning multiple subnets), in the previous example would be 192.168.0.1 - 192.168.0.254.

The DHCP scope is a subset of the subnet: 192.168.0.100 - 192.168.0.199.

Ideally, unless forced to by legacy issues, I prefer to keep static IP addresses and DHCP address ranges separate and distinct.

My personal convention is to do something like the following:
192.168.0.1 - 192.168.0.99 = static IP addresses for machines
192.168.0.100 - 192.168.0.199 = DHCP IP addresses for clients
192.168.0.200 - 192.168.0.249 = virtual IP addresses
192.168.0.254 - 192.168.0.250 = router IP addresses (starting at the top, working down)

This makes it easy to spot the role of an IP address based on its final digit, assuming a relatively small network segment and a subnet mask of 255.255.255.0

[latrosicarius]

Oh ok ty

So, I should create separate scopes for:

1-99 for various server machines
100-199 for various client machines
200-299 for "virtual IP addresses" (?!)
300-399 for routers (what's this "top-down" thing? lol)

Then if I did that, would I identify the server IP address in the wizard for all scopes, or just the 1-99 scope... same question for should I fill in the default gateway IP for all scopes or just the 300-399 scope?

[Paul Adams]

DHCP scopes should only specify which addresses should be used for DHCP clients, you do not need to specify all addresses in a subnet and there is no point in having scopes for anything else.

So just the one scope, 100-199, is fine for your DHCP clients.

I mentioned my addressing convention just to highlight the difference between a scope and a subnet.

Also, each part of an IP address can only go up to a maximum of 255 - and when this is the last digit this is reserved for a broadcast to all machines in that subnet.

Virtual addresses are for things like clusters, NLBS farms, firewalls with high availability, web servers, etc. - addresses that are either not tied to a physical machine or provide a specific service on a machine with another unique address.

By top-down I just meant that I start my numbering for routers at x.x.x.254, then the next is x.x.x.253, then x.x.x.252, and so on.
The other ranges I start at the bottom end and work up - so my first server would be x.x.x.1, my first DHCP client would be x.x.x.100 and my first virtual address x.x.x.200.

[latrosicarius]

I want to try your suggestion, but I don't want to screw up my network again, now that I have it working lol :-P