A server is limited in how many users it can serve in a given period of time, and once it hits that limit, the only options are to replace it with a newer, faster machine, or add another server and share the load between them. A load balancer can distribute connections among two or more servers, proportionally cutting the work each has to do. Load balancing can help with almost any kind of service, including HTTP, DNS, FTP, POP/IMAP, and SMTP. There are a number of open source load balancing applications, but one simple command-line load balancer, balance, remains one of the most popular available.
Ideally you should install a load balancer on a dedicated machine that can handle all the incoming connections, with a separate network interface for internal and external connections. However, none of this is necessary for the purposes of this article. To start testing balance, download the latest version from the project's Web site. Unpack it, build it, and install it as follows:
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