integration.rb

def valid_dns?
  return true if self.cname
  begin
    require 'resolv'
    heroku = Resolv.getaddresses("proxy.heroku.com")
    ip = Resolv.getaddress(self.landing.gsub('http://', ''))
    update_attribute(:cname, true) if heroku.include?(ip)
    return self.cname
  rescue
    return false
  end
end