how to count IPs in use

[Dima Fadeyev]

Hi, everyone

I'd like to find out how many IPs are in use (from the point of view of
my dhcp server). First I thought it would just be a matter of counting
the leases that have "binding state active" in dhcpd.leases. However
there are quite a few leases that have this line, but also have the
"ends" date in the past. So, I'm a bit confused. 

...
lease 81.143.246.98 {
  starts 1 2009/10/05 09:24:16;
  ends 1 2009/10/05 10:24:16;
  binding state active;
...

# date
Mon Oct  5 11:26:16 CEST 2009

Please, could anyone give me a hand. How do I find a number of IPs in
use?

Thanks and best regards.