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Split DHCP Configuration

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Last Modified: 2014-12-16
Setup DHCP split scope but second server won't give leases

I have configured Split DHCP Scope on Windows 2008 R2 Server.
I have scoped 80-20 on to each DHCP Server.
My problem is that the secondary DHCP server is not giving IP Address leases. and all machines are getting timed-out.
The Layer 3 Switch is 3560. Is their anything I need to do on L3 Switch.
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Subhashis SahooTechnical Consultant

Author

Commented:
I have come across a situation where in my company they want to use multiple DHCP servers to respond to queries, however they want to have the local DHCP server respond first and if that fails then they want the second DHCP server responding. The second DHCP server sits in a data center while the first is in the local office.

My question is
 
1. If I have 2 helper addresses configured, will the router sequentially choose the first and if it doesn't respond try the second helper OR will it forward the packet to both helper addresses and then its a race to whoever responds first?
 
I hope my question is clear and look forward to your expert advice.

So here I stopped the DHCP Service on the primary Server and tried testing few machines. But were getting timed out.

I have added ip helper-address for all DHCP Servers on all vlans.
AkinsdNetwork Administrator

Commented:
Both addresses configured with IP helper will be contacted. The PC will negotiate with the server that responds first which usually will be the server that's closest to the PC assuming all other factors (speed, processing time etc) are equal.

For your setup, you will need to put both servers in a cluster.
See link below on how to do that
http://technet.microsoft.com/en-us/library/hh831385.aspx

In your case, you will also need to fix connectivity to your server first to ensure that it will respond in the event the primary fails
Subhashis SahooTechnical Consultant

Author

Commented:
I was going through some links. Interestingly I found the below link:
http://serverfault.com/questions/355686/setup-dhcp-split-scope-but-second-server-wont-give-leases

Though I have given ip helper-address for both the DDHCP Servers, yet the second DHCP Server is not giving lease on a 80-20 setup.

Does the below config help on Core Switch. Is their any other thing that I need to check to make it work.
interface <on which the two DHCP Servers are connected>
switchport access vlan XX
** ip arp inspection trust
spanning-tree portfast
** ip dhcp snooping trust
end
AkinsdNetwork Administrator
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Subhashis SahooTechnical Consultant

Author

Commented:
Generally making a DHCP Server cluster, best suits for your Windows Server 2012.
As we have Windows 2008 R2 edition in our environment
AkinsdNetwork Administrator

Commented:
Server clustering has been in existence since Server 2000.

The steps in the link will guide you.

Your alternative is to use load balancers which I will assume you don't have right now. Server clustering is very easy to configure though just in case you feel intimidated. Just follow the steps

http://technet.microsoft.com/en-us/library/hh831385.aspx
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