Changing DHCP Servers

Posted on 2012-08-30
Last Modified: 2012-09-14
We have 11 clinics serviced by one data center but only 5 of them get their DHCP from us. The others have local servers. We are putting into place a DHCP server to replace the current one that is having hardware issues. I have created all the scopes and I have authorized it and unauthorized the old one. However. when I am trying to release - renew on a test machine it does not find the new DHCP server. I have even put in the Gateway router a line  (ip dhcp-server x.x.x.x) to point to the new dhcp server.

Am I missing something else? Yes I have activated the scopes and I can ping the new server, in fact I remote into the new server. I have checked any other routers and firewalls to see if they point dchp somewhere else and they do not.

Does this normally take awhile to get replicated and I need patience?
Question by:tnholt
    LVL 9

    Assisted Solution

    Run netsh dhcp show server command and see whether it is showing older DHCP server name if yes .then refer to remove older one.

    Author Comment

    OK - same issue but more information. The scope I need them to get is a x.x.100.x but the new DHCP Server is on the x.x.101.x subnet.

    I did run the netsh dhcp show server and it had the new dhcp server showing and the old one gone. So then i did the following.

     I created a subnet for the x.x.101.x, activated and immediately got a lease. But I want them to get the x.x.100.x subnet lease for those in the local clinic.
    LVL 23

    Assisted Solution

    by:Stelian Stan
    I think you need to move the database from old DHCP server to new one (
    LVL 1

    Accepted Solution

    Make sure the DHCP Helper is configured for the interface that represents their next gateway. That can get tricky if you have VLANS in place AND it depends on what platform their gateway is, as to how it's implemented. The DHCP Helper should point to the new DHCP server's IP address. Make sure you list out the configuration of the gateway at each location to confirm that the new DHCP helper address you added isn't in addition to the original one. On some implementations (HP, CISCO) you have to remove the old entry as well as add the new one.

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