 | The new IIS 6 process model upstages IIS 5 availability and reliability.
The new request-processing architecture in IIS 6.0 automatically detects memory leaks, access violations, and other errors. When these conditions occur, the underlying architecture provides fault tolerance and the ability to restart processes as necessary. Meanwhile, IIS 6.0 continues to queue requests without interrupting the user experience. |
 | The IIS compression utility enabled Microsoft.com engineers to compress its home page from 91K to 32K.
Turning on built-in compression with Windows Server 2003 and IIS 6.0 provides significant savings in monthly bandwidth charges. On a congested network, it is useful to compress HTTP responses. In IIS 5.0, compression was an Internet server application interface (ISAPI) filter with limitations. IIS 6.0 allows a much more granular configuration supporting file level compression. |
 | Previous Microsoft Data Access Components (MDAC) locking issues are resolved.
The resolution prevents an offline Microsoft SQL Server from blocking all data calls to other SQL Servers, which effectively takes a Web server offline. |
 | General IIS 6 error rate reporting is significantly reduced compared to IIS 5.
A change in the logging behavior of IIS6 results in up to a 50% reduction in reported internal server errors. In the past, Win2K would log a failed request and follow it with an additional Null 500 error. This logging behavior is eliminated in Windows Server 2003. |
 | Revamped security reduces default attack vulnerability and a more securable platform than Windows 2000 and IIS 5.
To reduce the attack surface of systems, IIS 6.0 is not installed by default on Windows Server 2003: administrators must explicitly select and install it. IIS 6.0 ships in a locked-down state, serving only static content. Using the Web service extension node, Web site administrators can enable or disable IIS functionality based on the individual needs of the organization. |
 | Tracing is instrumented in the operating system and its components.
This provides a large amount of data for troubleshooting a wide array of problems. |
 | The IIS 6 metabase is revamped to be completely XML based, providing a tremendous improvement in the manageability of servers across a site over IIS 5.0.
The XML-formatted, plain text metabase in IIS 6.0 provides improved backup and restore capabilities for servers that experience critical failures. It also provides for improved troubleshooting and metabase corruption recovery. Direct editing, using common text editing tools, provides greater manageability. |
 | Improved IIS and network load balancing (NLB) Event Logging provides a greater amount of information for troubleshooting problems.
Today, NLB logs which host caused the cluster to enter convergence on every machine in the cluster as well as each of the host IDs that are currently a part of the cluster. In Windows 2000, non-specific messages indicating only the current state of the server you were looking at. This really helps isolate incidents where a single machine is impacting the entire cluster. |
 | Resource Accounting and Quality-of-Service (QoS)
Quality-of-Service (QoS) ensures that particular components of the Web server, or specific content served by that server, do not take over all server resources, like memory or CPU cycles. It allows the administrator to control the resources being used by particular sites, application pools, the WWW service as a whole, and others. |
 | IIS can isolate an individual Web application or multiple sites into a self-contained process (called an application pool) that communicates directly with the operating system kernel.
This feature increases throughput and capacity of applications while offering more headroom on servers, effectively reducing hardware needs. These self-contained application pools prevent one application or site from disrupting the XML Web services or other Web applications on the server. |
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