Is this how pool balancing functions?

[Ian Anderson]

I have read through many threads about load balancing process but still
need some clarification.   I am currently running DHCP 3.4 in a load
balancing scenario.  I have several other pools as well and all of them
have similar messages.  


Aug 10 10:10:43 PRIMARY dhcpd: pool 9a5f830 KLF total 973  free 516
backup 432  lts -42 
Aug 10 10:10:08 SECONDARY dhcpd: pool 91367d0 KLF total 973  free 516
backup 432  lts 42

Aug 10 10:26:51 PRIMARY dhcpd: pool 99eab00 SEA total 3326  free 1821
backup 1465  lts -178
Aug 10 10:26:15 SECONDARY dhcpd: pool 90c1aa8 SEA total 3326  free 1821
backup 1465  lts 178


According to all the of documentation that I have read there should be
two events that occur during a POOL balance, "single-spaced pool"
request and the "two-spaced pool" response. I have many "single-spaced
pool" requests in my logs but no "two-spaced" to indicate that a
rebalance occurred.  Is this because the threshold of Free + Backup / 10
has not been reached? 

I also noticed 81 expired ip's in my dhcpd.leases file.  At what point
does dhcpd reclaim those addresses?   After restarting dhcpd the expired
leases were gone, but I don't want to restart dhcpd every time I get a
build up of expired leases. Is there a formula that dhcp uses to reclaim
expired leases?