Here's a script we're using to monitor the DNS entries for all our domains. This script is called once a day with a cron job.
The script reads a file containing a list of domains to monitor (one domain name per line). The path to this file can be configure with the variable DOMAINLIST.
Every time the script is run, it copies the results of the last run to OLDLOG (can be configured in the script) and writes the new results in NEWLOG (also configurable).
Then it performs a diff. If no changes occurred between the two runs, nothing happens. If something changed, an email is sent to the configured email addresses (variable EMAILS) containing the diff results.
#!/bin/bash
DOMAINLIST="/home/scripts/domains.list”
MAIL="/usr/bin/mail"EMAILS="henri.benoit@gmail.com xxx.xxx@xxx.com"
OLDLOG="/root/monitordns.OLD"NEWLOG="/root/monitordns.CURRENT"TEMPLOG="/root/monitordns.$$"
echo> $OLDLOGmv $NEWLOG $OLDLOG
while read linedo
echo "Checking $line:" | tee -a $NEWLOGdig +nocomments $line ANY | grep -v ";" | grep -v "^$" | awk '{ $2=""; print "'$line': "$0; }' | sort | tee -a $NEWLOGecho "" | tee -a $NEWLOG
done < $DOMAINLIST
echo "-------------------------------------------------------------"
diff -y --suppress-common-lines $OLDLOG $NEWLOG > $TEMPLOG
if [ -s $TEMPLOG ] ; then for EMAIL in $EMAILS do $MAIL -s "DNS status update" $EMAIL < $TEMPLOG donefirm -f $TEMPLOG