test-dns.sh

#!/usr/bin/env bash
set -e

DNS_SERVER=${1}
DOMAIN=${2:-google.com}
COUNT=${3:-100}

printf "Testing DNS for %s on %s ...\n" ${DOMAIN} ${DNS_SERVER}

for _ in $(seq 1 ${COUNT}); do
  start_time=$(date +'%s')
  result=$(dig ${DOMAIN} @${DNS_SERVER} || true)
  end_time=$(date +'%s')

  time=$(expr ${end_time} - ${start_time} || true)
  echo $(echo "${result}" | grep -oP ';; Query time: \K([0-9]+) msec') "${time}s"
  fi
done