redo-ifchange root-servers.net.zone
perl -lane 'print $F[$#F] if $F[3] =~ /^AA?/' < root-servers.net.zone |
while read addr ; do
    [ "${addr#*:}" = "$addr" ] && echo $addr ||
        sipcalc $addr | perl -lane 'print $F[$#F] if /^Compressed address/'
done