Need a perl/awk/shell script which will look for duplicates in /etc/hosts file?

Need a perl/awk/shell script which will look for duplicates in /etc/hosts file. the file file format is %26lt;IP%26gt;TAB%26lt;Hostname%26gt;TAB%26lt;Description%26gt;. The script will look for duplicate IP or hostname and once it is found, it will send e-mail to few users, also the scrip needs to be run using cron job at midnight. Thanks

Need a perl/awk/shell script which will look for duplicates in /etc/hosts file?
Are you allowed to be on the internet at work?