Good old "peer holds all free leases" appearing in a (formerly) very stable setup

Peter Rathlev peter at
Tue Feb 18 21:10:15 UTC 2014

On Tue, 2014-02-18 at 13:37 +0100, Nicolas Ecarnot wrote: 
> - isc dhcp 3.0.5-18.el5

I moved this to the top, since it's IMHO the most important thing. This
is an _ancient_ release. Upgrading could solve many strange problems.

> We have setup a complex DHCP infrastructure 5 years ago, and it is very 
> very stable and working very nicely :

Just to rub it in: DHCPd 3.0.5 was release in 2006. That's a lot more
than five years ago. ;-)

> shared-network dhcp51-dsi {
>    subnet netmask {
>      option subnet-mask;
>      option routers;
>      option domain-name-servers,;
>    }
>    pool {
>      allow members of "oldStableClass";
>      failover peer "serv-net-adm1_serv-net-adms1";
>      deny dynamic bootp clients;
>      range;
>    }

I'm not an authority on this, but I have always placed "pool" statements
inside the "subnet" statements. I don't know if one is supposed to do
that but it looks more intuitive for me. (Inheritance shouldn't be a
problem with your method though AFAIK.)

> I had a (read-only) look at the lease file, and it does not show any 
> reference to this subnet, though it appears in the log file when 
> restarting this server (net-adm1).

Hmm... At least on ISC DHCP v4.x I would expect "unknown network
segment" if the pool just didn't exist. OTOH if it's not in the leases
file (which every address free or not would be in a failover setup (on
v4 at least)) then something is really wrong.

How many "subnet" statements and "pool" statements do you have? Could
you have run into some kind of limit in the software? Does adding yet
another subnet change things in any way?


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