IIS Architecture Overview

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)