load balancing

Definition of load balancing in The Network Encyclopedia.

What is Load Balancing?

Providing access to resources on a group of servers in such a way that the workload of serving clients is shared among the servers. Numerous vendors supply hardware and software-based load balancing solutions for enterprise networking.

Microsoft in particular implements various forms of load balancing in its products, including the following:

  • Microsoft Cluster Server (or Windows Clustering in Windows 2000):
    Provides static load balancing for high availability of shared resources. Each node in a cluster shares its own resources or applications, and if failover occurs, the nodes still running can assume the services of the other nodes. This leads to load balancing and high performance.


  • Microsoft Proxy Server version 2:
    Provides load balancing of Winsock Proxy (WSP) client connections across several proxy servers by specifying the servers’ IP addresses in the mspclnt.ini file, which is copied from the server to the client when the WSP client is set up. This file enables clients to randomly select which proxy server to use each time they issue a proxy request.


  • Microsoft DNS Service in Windows NT Server:
    Supports round-robin DNS service. If you list several IP addresses for the same host name in a DNS zone file, clients connecting to the DNS server to resolve the host name receive the IP addresses in round-robin fashion. This is a simple form of load balancing.


  • Microsoft SNA Server version 4:
    Provides load balancing and fault tolerance for connectivity with AS/400 systems.


Various network devices can also implement load balancing. For example, routers use load balancing when routing tables indicate that two or more routes to a destination have the same cost. This use of routers allows you to use different LAN segments more effectively, resulting in greater availability of overall network bandwidth.