[CentOS] DHCP server failover: advise is needed

Valeri Galtsev

galtsev at kicp.uchicago.edu
Fri Nov 22 17:10:26 UTC 2019

Dear Experts,

I was running ISC DHCP server for longer than I would care to remember. 
Now I decided to climb out of the cave and configure failover set 
(primary-secondary), and I seem to hit brick wall, which I need help 
with. I only need IP v4, no v6, which may simplify things.

Could someone point to a description of working DHCP failover configuration?

I do not want to make two independent DHCP servers handling half of the 
pool each. We are not that rich as far as IP space is concerned.

I am not married to ISC DHCP server, so any one I will do, because:

My current configuration is something that was gradually migrated and/or 
adjusted through several generations of systems, and server versions 
over the years. It works. When I tried to incorporate what I need for 
failover following ISC documentation, and some people's guides, I 
discovered, I need more sophisticated structure of sections and 
subsections, which I figured out finally. But the annoying part was: in 
ISC documentation I failed to find general stricture of which section 
can appear inside which; like:

a {
  b {
   c {


You can create each of sections/subsections following documentation, but 
to put them together making consistent config file you (I at least) have 
to figure on your own which section goes inside of which.

So, I am not married to ISC DHCP server, we didn't get along now as far 
as my use of documentation is concerned. Anything that works - with 
failover! I am going to have it set up on FreeBSD, but if something 
works on Linux, I likely will be able to reproduce it on FreeBSD.

Thanks in advance for all your answers!

Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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