Find duplicate PTRs in a zone file
For any RFC compliant reverse zone file including BIND / named, where the first field is the last octet:
for i in `egrep '^[0-9]{1,3}' reverse.rev | awk '{print $1}' | sort -n | uniq -d` ; do egrep ^${i} reverse.rev;done
As awk is used it will still work if spaces or tabs are used. Please
feel free to contact me if you find an instance
where it does not work.