DNS or rDNS and PTR records
If you know the hostname you want to track then it is much easier to use DNS.
myprecious.somedomain will always show the IP address of myprecious whenever it still has a valid lease.
So this is as much a DNS as an rDNS risk.
rDNS is just one way to find valid hostnames, but any (brute force) DNS query of a domain would give a more complete overview.
And if rDNS is considered a greater risk than DNS then disabling the creation of PTR records for DHCP leases solves that problem.