DNS Response Time Checker

dns.zsh

#!/bin/zsh -

#===============================================================================
#
#          FILE: dns-tests.zsh
#
#         USAGE: ./dns-tests.sh google.fr
#
#   DESCRIPTION: DNS Response Time Checker
#
#  REQUIREMENTS: dig
#        AUTHOR: David Dérus
#  ORGANIZATION:
#       CREATED: 13.05.2017 11:58
#      REVISION: 1.1
#
#===============================================================================

set -o nounset                              # Treat unset variables as an error

# DNS_SERVERS:
# - 8.8.8.8 = Google DNS
# - 208.67.222.222 = OpenDNS
DNS_SERVERS=(8.8.8.8 208.67.222.222)
TEST_DOMAINS=("$@")

if [ $# -eq 0 ]; then
  echo "You must provide at least one valid domain name to resolve against"
  exit 1
fi

echo "Starting test at `date +%Y-%m-%d:%H:%M:%S`"
echo "Using test domains: ${TEST_DOMAINS[*]}"
echo

for domain in ${TEST_DOMAINS[@]}; do
  echo "= Querying for $domain:\n"

  for dns in ${DNS_SERVERS[@]}; do
    echo -ne "> Using DNS $dns: "

    dig_output=`dig "@$dns" $domain`
    query_time=`echo $dig_output | egrep -o "Query time: \d+ \w+" | cut -c 13-`
    response_addresses=(`echo $dig_output | egrep -o "$domain.\s+\d+\s+IN\s+A\s+.+" | egrep -o "\d+.\d+.\d+.\d+$"`)

    if [[ -z "$response_addresses" ]]; then
      echo "No results"
    else
      echo "Found ${response_addresses[*]} in $query_time"
    fi
  done

  echo
done

exit 0