I'm looking for a simple bash script that can be run using cron that will delete dns zones (in cPanel) not pinging or resolving. Do you know any script that will be capable of handling that?

Create a script as follows ,
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#!/bin/bash
for i in `cat /etc/userdomains | cut -d ":" -f1 | uniq | sort -n| grep -v '*'`
do
/scripts/killdns $i
done
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