IIS Architecture Overview

Article
06/16/2017

IIS architecture has changed over time. Understanding the architectural features of a specific version of IIS can help you decide how to design an application for IIS.

Comparison of IIS Versions

The following table summarizes the important differences between versions of IIS.

Feature	IIS 4.0	IIS 5.0	IIS 5.1	IIS 6.0
Platform	NT4	Windows 2000	Windows XP Professional	Windows Server 2003
Architecture	32-bit processor	32-bit processor	32-bit and 64-bit processors	32-bit and 64-bit processors
Application process model	TCP/IP kernel Inetinfo.exe runs in-process applications (low isolation) MTX.exe runs out-of-process applications (high isolation)	TCP/IP kernel Inetinfo.exe runs in-process applications (low isolation) Multiple DLLhost.exe processes run pooled-process or out-of-process applications (medium or high isolation)	TCP/IP kernel Inetinfo.exe runs in-process applications (low isolation) Multiple DLLhost.exe processes run pooled-process or out-of-process applications (medium or high isolation)	HTTP.sys kernel When IIS is running in IIS 5.0 isolation mode: Same process model as for IIS 5.0 When IIS is running in worker process isolation mode: W3Wp.exe (multiple worker processes) For more information about the IIS 6.0 process model, see Worker Processes in IIS 6.0
Metabase configuration file type	Binary	Binary	Binary	XML-formatted
Security	Windows authentication SSL	Windows authentication SSL Kerberos	Windows authentication SSL Kerberos Web Server Certificate Wizard	Windows authentication SSL Kerberos Web Server Certificate Wizard Microsoft. NET Passport support
Remote administration	HTMLA	HTMLA	No HTMLA Terminal Services	Remote Administration Tool (HTML) Web Server Appliance Kit (SAK) Terminal Services
Administration technologies	ADSI and ABO	ADSI and ABO	ADSI and ABO	ADSI, WMI, and ABO
Cluster support	Windows support	IIS clustering	Windows support	Windows support
WWW services	IIS on NT 4.0 Personal Web Manager on Windows 95 and Windows 98	IIS on Windows 2000 Server and Windows 2000 Professional (IIS is not installed by default on Windows 2000 Professional)	IIS on Windows XP Professional (IIS is not installed by default)	IIS on Windows Server 2003 (IIS is not installed by default)