Introduction to IIS 6 and Changes in IIS 6 from earlier versions

IIS 6.0 has been totally re-designed with a new request processing architecture that has the benefits of high isolation without incurring the out-of-process cost, as well as much higher levels of reliability and scalability.


IIS 6.0 runs a server in one of two distinct request processing models, called application isolation modes. Application isolation is the separation of applications by process boundaries that prevents one application or Web site from affecting another and reduces the time that you spend restarting services to correct problems related to applications.

Changes in IIS 6.0 from earlier versions of IIS:

1. IIS 6.0 uses different application request processing model. Since IIS 6.0 can work under two different isolation modes, it can have two different processes. If IIS 6.0 is running under worker process isolation mode then IIS 6.0 will run under w3wp.exe. If IIS 6.0 is running under IIS 5 isolation mode with in process isolation then it will run under inetinfo.exe. If IIS 6.0 is running with out-of-process request processing then it will run under dllhost.exe. For more details about in-process & out-of-process
2. IIS 6.0 uses XML for metabase configurations. Earlier versions were using binary instead of XML
3. IIS 6.0 uses HTTP.sys instead of TCP/IP kernel (Windows Socket APIs)
4. It also supports .Net passport support for security