The audit trail log records a history of activity logged by DNS and DHCP servers. You can use the Audit Trail log to diagnose network trends. A DNS audit trail would include a history of DNS queries and the hosts requesting them. A DHCP audit trail would include a history of address assignments, including which host had an address during a given period of time and a list of addresses that had already been in use when pinged.
See Configuring DNS Auditing for information about configuring a DNS server for auditing. See Configuring DHCP Auditing for information about configuring a DHCP server for auditing.