Windows blocks pings: dup IPs being handed out

[Colin McInnes]

Under default Windows firewalls, pings are blocked. So when the lease
pool is all used up, and a request comes in, a ping is sent out to see
if an address is still in use. But the Windows boxes don't respond,
because they block pings. So an address is handed out under the
assumption that the unit using it is offline, but it's already in use,
just not properly responding.

What alternatives to verifying addresses via ping are reasonable
solutions for the server to check if an IP is still in use (short of
making lease times much shorter)?