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Windows 2003 DHCP rule

We have a small domain network in one of our sites, using Windows server 2003 as domain controller and the router  is the DHCP ..
I want to add the DHCP rule to DC.

1- Can I set DHCP rule on DC by MAC address?
2- If I add the rule - and activate it ? Is it starting to work immediately ?
3- I need to stop DHCP on router and then activate on DC ? what will happen if both are active at the same time ?
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it_saigeDeveloper
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Distinguished Expert 2019
Commented:
  1. Yes you can reserve IP's based on MAC.
  2. Yes it starts working immediately.
  3. By default Windows will automatically disable the DHCP service if another DHCP server is detected (there is a registry setting to override this) but you will want to disable the DHCP on the router before you activate the DHCP on the server.  Any devices that currently have IP addresses will continue to use their assigned address until their lease expires or a request to obtain a new address is issued.

Leaving both the router and the DC running DHCP will potentially cause ip conflicts because they both do not read from or update the same DHCP pool.  

Once you have activated the DHCP service on the DC, you should go to each workstation and issue the following command:
ipconfig /release && ipconfig /flushdns && ipconfig /renew && ipconfig /registerdns

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-saige-
JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018
Commented:
You can use DHCP Reservations on the Server as was noted in the prior post.  We use DHCP reservations here at a client (and other clients as well).

We use the Server for DHCP and NOT the router. Please remove DHCP from the router.

Now, in a smaller environment, Routers can do DHCP Reservation. I do this on Cisco RV routers .

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Commented:
Do I must go to each workstation and issue a command ?
Today my router assign addresses from 192.168.100 to -252 for laptops with no static IP..
so all suppose to disconnect at the end of the day when they leave office.
all my static addresses are below 100..
Business Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018
Commented:
If you do DHCP reservations, leave Workstations as DHCP and nothing to do there.  Just the server
JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

Commented:
Thanks and good luck with reservations - they work fine
kevinhsiehNetwork Engineer
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Commented:
@it_saige, it is NOT TRUE that Windows Server will disable DHCP if it detects another DHCP server on the network. That is only correct for SBS editions. Regular Windows Server will allow multiple DHCP servers on a network segment, and it fact that is recommended for multi-server environments so that there is high availability for the DHCP services.
it_saigeDeveloper
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Distinguished Expert 2019

Commented:
@kevinhsieh - Thanks for the clarification.  I knew there were instances where the DHCP service would be turned off.  Just wanted to ensure that all the bases were covered.  ;)

-saige-

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