Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a very specific setup of servers which netboot off a san. All of them provide identical functionality. There are no other machines in this netblock.

Each machine boots from an iscsi image which are all set for dhcp.

What I want to know is, can I run 2 dhcp servers (not in failover mode), where each dhcp server has an identical setup and is a known host.

i.e. the dhcpd.conf file has each host pre-defined by mac address and has been given an IP address.

If I understand dhcp correctly, the client will grab the first address it sees.

I've tried isc dhcpd in failover mode but I've been having problems with it. When the slave dhcp goes down, I loose connectivity to the machines momentarily. However, when it comes back up again, connectivity is lost for (much longer than the lease time) until I reboot the master and that comes back online. I wasn't predefining all the servers at that point.

So the question isn't so much about isc dhcpd, but could be for any dhcp server. I'm using isc dhcpd though. I assume both servers will respond and would give out the same answer. But will either cause problems for the client when 2 answers are received? Should I set one as authoritive and the other as not or would having them both authoritive been OK?

share|improve this question
Please clarify " When the slave dhcp goes down, I loose connectivity to the machines momentarily.". Are you saying when the slave DHCP server goes down, the client servers that receive DHCP leases from the DHCP servers lose network connectivity? – longneck Jan 25 '13 at 17:30
"If I understand dhcp correctly, the client will grab the first address it sees." - No. the DHCP server gives the client an address based on its configuration. The client doesn't 'grab the first address it sees' from the server. – August Jan 25 '13 at 17:31
What is your reasoning for having 2 DHCP servers in the first place? – August Jan 25 '13 at 17:37
August. Redundancy. – Matt Jan 25 '13 at 17:51
August - What I meant by grab the first address it sees, is take the first address it is given by a DHCP server and ignore the other leases it is provided with. If the servers are set to always give a particular client the same address it both answers will be nearly identical. – Matt Jan 25 '13 at 17:53

If both settings are guaranteed identical, I don't see how it could hurt. If they're not, it will hurt.

You could also migrate your DHCP to two Windows Server 2012, which does this in a way that works, IME.

share|improve this answer

Your Answer


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.