Dedicated load-balancing appliances are available both in physical and virtual formats. The difference between the physical and virtual versions will differ from one vendor to another, so it is important to understand the impact of choosing one over the other.

Dedicated load balancers often have the capability to balance client connections based on a number of different factors. The following load-balancing metrics are not from any specific vendor, but are simply examples of the metrics that various solutions use:

• Server load
• Recent server response times
• Server up/down status
• Number of active connections
• Geographic location
• How much traffic has been assigned to a given host

In addition to any advanced features, dedicated load-balancing appliances do not require additional resources on the servers they are balancing traffic for, which is one additional advantage they have over using Microsoft NLB.