Denied DNS Requests
From James Dooley's Wiki
Overview
Find denied queries against DNS, good for finding sites that are no longer hosted or do not have valid DNS records.
Script
[bash,n]
cat /var/log/messages | grep named | grep denied | cut -d "'" -f2 | cut -d "/" -f1 | sort | uniq -ci | sort -nr > /root/denied_dns.txt
