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I have just started learning about the DHCP server. I know that if i use window 2008 server as DHCP server then it can give IP to clients.

But all other computers are linked to router and i think router will give them ip

so if i make my computer with as dhcp server.

How will other clients get IP from me

Sorry for ignorance but i want to clear my doubts

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multiple DHCP servers typically results in a "race" to supply IP addresses, which is the worse of both worlds - you end up with machines that work intermittently as they get addresses from first one DHCP server then the other. The best solution is to turn off the unwanted DHCP server - in the case of your router this is usually one of the configurable options.

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Agreed. The only time I could ever see justification of multiple DHCP servers would be in one large geographically dispersed subnet, and where each DHCP server separate ranges. Not at all a common condition. – Matt Simmons Dec 13 '09 at 23:41
IN my company i have few macs and few PC. I have seen that if my DHCP server is down then PC won't get IP but MAC still gets it. Why is that – John Dec 13 '09 at 23:55
The MAC is probably re-using the remnants of the lease it had last time, if it hadn't expired yet. Windows computers don't seem to do that. – David Mackintosh Dec 14 '09 at 3:41
@Matt: It can be very useful to have redundancy on your DHCP service. isc-dhcp is active-active clusterable so that when the hardware dies, you don't hear a thousand screams from your users. – MikeyB Dec 14 '09 at 4:26

A DHCP server is by no means a natural part of a router. Actually, a DHCP server and a router doesn't even operate on the same network layer.

That said, when it comes to home network equipment it's is common for the router and the DHCP server to be integrated into the same physical device. This is merely for convenience, there is nothing which says they have to be the same device.

Hence, as MikeT505 already have said, just turn of the DHCP server in your so called "router" device, and your Windows 2008 server should be able to function as a DHCP server without interruption. Also know that the specific ip address of the DHCP server doesn't really matters, as DHCP work on a broadcast basis.

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It means if my computer is connected to router and is acting as dhcp server then all IPs will be given by my computer? IF my computer is turned off then what happens to other computers if router is on and others are connected to it. Will they receive internet or not – John Dec 13 '09 at 23:54

You will need to turn DHCP service off, on your router in order for your DHCP server to give out IP addresses to your computers.

When you restart your computers they should automatically recieve an IP address from your DHCP Server (SBS server). (Note this will not happen if your PC's have static IP addresses)

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By static means if user has defined their own ip address in properties I have defined few reserved IPs in router. But i don't understand that window is serving as DHCP but still i get those reserved which i have dined in router, but DHCP in router is turned off. So it means window talks with router baout reserved Ip – John Dec 13 '09 at 23:48

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