cat opennic-roothints.bash
#!/bin/bash
# 2012, Falk

# Whats the IPv4 address of NS0?
NS0="75.127.96.89"

nameservers=`dig axfr dns.opennic.glue @${NS0}| egrep '.dns.opennic.glue. [0-9]{1,6} IN' | cut -d " " -f 1 | uniq`
tmpfile="/tmp/opennic-roothints.$RANDOM"

function rootHints()
{
dig . NS @${1} | egrep "^\." | awk '{ print $5 }' | sort | uniq
}

rootHints ${NS0} > ${tmpfile}

for server in ${nameservers}
do
    thisHints=`rootHints ${server}`
    if [ "${thisHints}" = "`cat ${tmpfile}`" ]; then
        # Everything is in sync with NS0
        echo ${server%?},SYNC
    else
        # Something bad happened. What exactly?
        # Is the server down?
        if [ `nc -zu -w 60 ${server} 53; echo $?` -ne 0 ]; then
                echo ${server%?},NOT_RESPONDING
                continue
        fi
        # Is the hints file empty?
        if [ -z "${thisHints}" ]; then
            echo ${server%?},HINTS_EMPTY
        fi
        # Or is the server just unsync? Then print a diff!
        echo ${server%?},UNSYNC
        diff <(cat ${tmpfile}) <(echo ${thisHints})
        echo ${thisHints}
    fi
done

rm ${tmpfile}