dns name sever query comparison

nsq_compare.sh

#!/usr/bin/env bash

nameserver_source="a.iana-servers.net"
nameserver_comparison="b.iana-servers.net"
dns_records="
example.com a
ftp.example.com a
mail.example.com a
ns1.example.com a

www.example.com cname

example.com mx

example.com txt

example.com ns

example.com soa
"

source_output=""
comparison_output=""
NEWLINE=$'\n'
while read domain
do
  if [[ $domain = "" ]]; then
    source_output+="${NEWLINE}"
    comparison_output+="${NEWLINE}"
    continue
  fi

  if [[ $domain =~ NS$ ]]; then
    domain+=" +authority"
  fi

  source_output+="$(dig +nocmd +noall +answer @${nameserver_source} ${domain} | grep -v "^;")${NEWLINE}"
  comparison_output+="$(dig +nocmd +noall +answer @${nameserver_comparison} ${domain} | grep -v "^;")${NEWLINE}"
done <  <(echo "${dns_records}")

echo "==> ${nameserver_source}"
echo "${source_output}"

echo "==> ${nameserver_comparison}"
echo "${comparison_output}"