Take the 2-minute tour ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

On my network, I have 3 remote sites and one local that all receive DHCP through our central dhcp server.

all the sites have ASAs with dhcprelay and so on.

I have two domain controllers - is it possible to set the second dc as secondary dhcp server, add the information to the ASA - and use it as a failover incase the primary dhcp server is offline?

would this cause problems?

thanks

share|improve this question
    
possible duplicate of Two DHCP servers on the same network –  GregD Apr 26 '11 at 13:38
    
How long are your leases and why do you think you need a backup DHCP server? –  GregD Apr 26 '11 at 13:41
    
Sorry about the duplicate. Because all pcs on my network get there IP from the DHCP server which as the primary dc. If the primary dc would go offline for whatever reason for a long amount of time, i want the dc2 to be able to handle the dhcp as well as dns and a/d –  Jeff Apr 26 '11 at 13:50
    
possible duplicate of Can I have multiple DHCP servers on one network? –  RobM Sep 1 '12 at 21:34
add comment

2 Answers 2

up vote 6 down vote accepted

Yes, this is possible and will not cause problems as long as it's configured properly. To setup the second DHCP server as a "failover" you will want to divide up the scopes DHCP 1 is serving. To do this you would configure the same scopes on DHCP 2 as there are on DHCP 1. You would then exclude a percentage of the scope on DHCP 1 and then exclude the opposite percentage of the scope on DHCP 2. This way together they would be serving the full scope.

Microsoft recommends using an 80% / 20% divide but there is debate on what works best.

Make sure that if you have any reservations set that they are setup on the secondary DHCP server (if they fall within the scope that will be served from that server).

         DHCP 1                     DHCP 2

scope    192.168.1.0/24             192.168.1.0/24
exclude  192.168.205 - 254          192.168.1.1 - 204

share|improve this answer
    
Thanks for the information –  Jeff Apr 26 '11 at 13:49
add comment

Yes, you can do this, probably the easiest way is just to split the ranges.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.