Microsoft ISA Server Editions

ISA 2004 Standard Edition does support Network Load Balancing (NLB), but only through the host Windows Server operating system. In other words, NLB is completely independent of the ISA Standard configuration, and is configured as part of the underlying server operating system.

The Enterprise Edition is used when you have a larger, enterprise-level network that requires multiple servers, multiple sites, or servers that are installed together as an array. Although Enterprise Edition offers the same functionality and roles as the Standard Edition, it offers 3 important advantages over Standard:

First, ISA Server Enterprise Edition stores its configuration data in a central location, on a server configured as a Configuration Storage Server. All Enterprise Edition servers in the organization then get their configuration data from this server. When changes are made to the configuration, they only have to be made in one place, and are then propagated out to the other servers. Unlike previous versions of ISA, Enterprise Edition also stores its information in the Active Directory Application Mode database structure, so being part of an AD domain and modifying the schema is no longer necessary for centralized storage.

Second, ISA Enterprise Edition also supports the Cache Array Routing Protocol, or CARP, when configured in an array with other ISA servers. This means that the cached content is common to all array members, and when a client requests content that has been cached, it can come from any server in the array that happens to be in possession of that content.

Finally, Enterprise Edition also has built-in NLB capabilities, separate from the underlying Windows operating system, that are part of the ISA configuration itself. This enables NLB to be configured and optimized as part of the array configuration.

Those are the main differences between the two editions. We’ll cover other differences and similarities between Standard Edition and Enterprise Edition as they come up during the course of this series. The other differences we’ll talk about during this installment are the differences between ISA Server 2004 and ISA 2000, and the improvements that have been made over 2000.

Although ISA Server 2004 is similar to its predecessor, ISA Server 2000, there are some significant differences in terms of functionality, expanded capabilities, and configuration. ISA server 2004 is much more scalable and flexible in the way it supports networks. Here are some of the features of ISA 2004 compared to ISA 2000.