def hostnames_ips
      @hostnames.map do |hostname|
        ips.select { |ip, host| host == hostname }.keys
      end.flatten
    end
def hostnames_ips
      @hostnames.map do |hostname|
        ips.select { |ip, host| host == hostname }.keys
      end.flatten
    end
Orders ips by hostnames

 The purpose of this method is to sort ips of hostnames so it tries all IPs of hostname 1,
 then all IPs of hostname 2, etc

 == Return
 @return [Array] array of ips ordered by hostnames