#!/bin/bash
if [ ! "$1" ]; then
echo "Missing parameter"
exit 1
fi
NS=$(dig +short -t NS "$1")
RESULT=""
while read -r server; do
if [[ "$2" -ne "6" ]]; then
IP4=$(dig +short -t A "$server")
RESULT="$RESULT""$IP4"$'\n'
fi
if [[ "$2" -ne "4" ]]; then
IP6=$(dig +short -t AAAA "$server")
RESULT="$RESULT""$IP6"$'\n'
fi
done <<< "$NS"
echo "$RESULT" | grep -v '^$'