!/usr/local/bin/bash

checkdns () {
CHECKNAME="your_hostname.com"
DIGCOM=`dig \@$TARGETHOST $CHECKNAME | grep ";; ANSWER" | wc -l`
if [ $DIGCOM -lt 1 ]; then
        STATUS=2
        STATUSPRINT=CRITICAL
else
        STATUS=0
        STATUSPRINT=OK
fi

echo "$STATUSPRINT - DNS resolution for $CHECKNAME"
exit $STATUS
}

while getopts :h: OPTIONS
do
case $OPTIONS in
        h) TARGETHOST=$OPTARG;;
        *) echo "Invalid Command Line Option";;
esac
done
checkdns