The dispatcher-based web server load balancing architecture can improve the performance of popular web servers. When the backend servers have different computational power, the system must use the real-time loading information as the decision making criteria. In this paper, we proposed a dispatcher architecture that uses the remaining capacity of each backend servers to decide the most appropriate server. In addition to improve the performance, the system can also use the remaining capacity algorithm to reduce the cost when the web side does not have frequent burst request. For example, the course registration ticket reservation systems have burst requests only several times a year. The proposed architecture can use the remaining capacity of other servers such DNS or MAIL server to share the load in the burst request period. The simulation results show that using the remaining capacity of both DNS and MAIL server can achieve similar performance compared to using another dedicated web server.