Happy new year !
A site I visited over the Christmas period was experiencing issues with DNS. There were no obvious faults other than an exceedingly large number of records in a somewhat small environment.
I discovered that the DHCP lease time was set to 8 hours and that scavenging was not set at all.
A few days later after the cycle had completed and 875 scavenged nodes later all is healthy again. Not to mention a decrease in network traffic.