Checks if the given domain is reachable as long as there is a 200 OK coming back. Super simple! ;)

gistfile1.rb

require 'net/http'
require 'date'

# Fetches the first argument passed to the script, if no is given 
# it raises and error with this simple custom message.
unless @domain = ARGV.first
  raise "You need to pass in a domain like www.6wunderkinder.com"
end

puts "[#{DateTime.now}] Started the DNS check for #{@domain}..."

# Sends a simple GET request to the given domain and checks 
# if the response was 200 OK.
def do_request
  uri = URI("http://#{@domain}")
  response = Net::HTTP.get_response(uri)
  response.is_a?(Net::HTTPOK)
end

# Puts a NotFound message and sleeps for 60 seconds as long as the 
# request is not a 200 OK. If there is a 200 OK coming back it puts
# the success message and the script terminates.
begin
  while do_request == false
    puts "[#{DateTime.now}] NotFound: #{@domain}..."
    sleep 60
  end

  puts "[#{DateTime.now}] Success: #{@domain} is up and running!"
  puts "[#{DateTime.now}] Done."

# If something went wrong, any error occurs the script terminates 
# with a error message.
rescue => e
  puts "[#{DateTime.now}] Error: We couldn't reach #{@domain}!"
  puts "[#{DateTime.now}] Error: #{e.message}"
  puts "[#{DateTime.now}] Canceled."
end