Setting up a 2nd DHCP server


I setup a DHCP server at my work a couple of years ago and it is working jsut fine.  I needed to setup some DHCP - Relay rules on our main Router, to enable DHCP to connect to a specific VLan, that I setup as well.

My question is regarding the setup of a 2nd DHCP router, for redundancy.  Currenlty I get very nervous if I restart the existing DHCP server becasue it is the only DHCP server at my work.

My questions are,

1.  Is it a good idea to have a 2nd DHCP server, for backup or reducndancy purposes?

2.  Should I have them duplexed, or can I have 2 DHCP server running simultaneously?

3.  What else would be required in setting up a 2nd DHCP server?
        a.  Is there anything I need to be careful of in setting up a 2nd active DHCP Server, will the 2 DHCP server have any problems sendign out IP  addresses and working working together with the same rules(reserved IP's)?

Currently the 1 DHCP server is runnig on Wondows 2003 Server Std edition.
PkafkasNetwork EngineerAsked:
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Darius GhassemCommented:
I would setup a split scope which will allow for redundancy.
You can setup DHCP with SPLIT Scope.

A Dynamic Host Configuration Protocol (DHCP) split-scope configuration using multiple DHCP servers allows for increased fault tolerance and redundancy over using only one DHCP server.
Using Split-Scope Configurations

How to configure split-scope using wizard

This is the best solution in your scenario. one server becomes unavailable, the other server can take its place and continue to lease new IP addresses or renew existing clients

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PkafkasNetwork EngineerAuthor Commented:
Ok, I have a few questions about this plan:

1.  Will I need to make another routing rule, on our Router, to allow DHCP relay from teh 2nd DHCP server?

2.  Will I need to setup the 2nd DHCP server before I initiate the split scope option?
       a.  it appears from the configuratin wizard above, that is the case.
Darius GhassemCommented:
If you are giving out IPs across subnets over a router then yes you will need to enable DHCP relay.

And IP helper address on the vlan interface pointing to the new dhcp server.
Split scopes are a wonderful thing. MS usually recommends an 80/20 split, but I prefer a 50/50 to make sure that if one goes out you have enough ip addresses available.
PkafkasNetwork EngineerAuthor Commented:
Ok, I like the idea of having a 50/50 scenario as well.  I would like to review my process just to make sure I am not forgetting anyhting.

1.  I have a working DHCP server.
         a.  DHCP Relay is enabled on our router.
         b.  This DHCP server is sending IP addresses across to a different subnet.
         c.  This DHCP server is on our Defaul VLan with an IP scheme os 192.X.X.X .
               i.  The Addresses least out are 10.220.210.X/24.

2.  I would like to add a secondary DHCP server that I have created on a new Servers V-Lan.
        a.  This server VLan has an IP scheme of 10.220.110.X/25 .
               i.  The addresses to be leased are the same as above, 10.220.210.X/24.
        b.  If I understand the process correctly I will have to do sokething like steps shown below.


1.  Setup the DHCP Server service on another server.
        a.  I have to enter some IP Range settings for the 2nd server as I have on the 1st DHCP server correct?
             i. IP addresses 'start' & 'End' .

2.  Then follow the Split-Scope instructions found in:

3.  Then enable a routing rule to allow DHCP leases to be sent over the network, from the new 2nd DHCP Server.
Darius GhassemCommented:
PkafkasNetwork EngineerAuthor Commented:
Do I have to enter the same IP ranges on the 2nd DHCP server as on the 1st DHCP server?

I had a type-o in my previous commnet.  I put 'same' and I meant to type 'same'.
yes, but the ip range will make the difference iduring the split con configuration screen where you specify which server will give which ip's.... start IP and end IP..
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Windows Server 2003

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