gistfile1.sh

#!/bin/bash

function hosts_fetch {
  mkdir -p ./tmp
  dig heroku.com > ./tmp/dig.list
}

function hosts {
  sed -n '/^;; ANSWER SECTION:$/,/^$/ {
            /^heroku\.com\..*[^.0-9]\([.0-9]*\)$/ {
              s//\1/
              p
            }
          }' < ./tmp/dig.list
}

function trial_run {
  for host in $(hosts)
  do
    echo "##  $host"
    time curl -I -H 'Host: heroku.com' http://$host
  done
}