DNS Audit
The DNS Audit tool helps you locate DNS database errors by scanning a range of IP addresses and performing reverse DNS lookups for each address. If DNS Audit receives a DNS response for an address, it attempts a forward DNS lookup to verify that the forward lookup resolves to the originally-scanned IP address.
Any errors found during the scan are highlighted. You can also filter the results to show the reverse DNS errors, the IP addresses that did not resolve, or forward DNS errors.