test-subdomains.sh

#!/bin/bash
TESTDOMAIN=${1:-'embed.apiary.io'}
trap "exit 1" INT

OUTPUTLINES=`dig +short ${TESTDOMAIN}. @8.8.8.8 | wc -l`

servers="
208.80.68.212
204.14.152.2
204.14.152.5
"

while true
do
  for server in $servers
  do
    lines=`dig +time=1 +short ${TESTDOMAIN}. @$server | wc -l`
    test $lines -ne $OUTPUTLINES && { echo; echo $server ERROR; } >&2 || {
      echo -n . >&2
    }
    sleep 0.1
  done
done