Working with URL Rewrite modules in IIS7+, you'll notice that rewrite rules defined in a parent directory's web.config automatically apply to all subdirectories. While this behavior is generally useful, it becomes problematic when:

• CMS admin areas need original URLs
• Subdirectories contain different applications
• Special API endpoints require raw query strings

Most implementations handle this by placing web.config files in subdirectories with either:

or the nuclear option:

The maintenance overhead grows with each new subdirectory added to the project.

IIS actually provides a cleaner solution through the <location> tag with inheritInChildApplications="false":

When using this approach:

• The path="." indicates the current directory
• Works with IIS7+ (requires Application Host Compatibility)
• Affects all configuration sections within the tag
• Combine with enabled="true/false" for dynamic control

For cases where some subdirectories should inherit rules while others shouldn't:

When implementing clean URL patterns in IIS7+, many developers encounter an unexpected behavior where rewrite rules automatically propagate to all subdirectories. This becomes particularly problematic in CMS environments where admin panels or API endpoints reside in subfolders.

The standard approach requires manual intervention in each subdirectory's web.config:

<system.webServer>
    <rewrite>
        <rules>
            <remove name="Clean URLs" />
        </rules>
    </rewrite>
</system.webServer>

While functional, this solution creates maintenance overhead and potential points of failure.

IIS doesn't provide direct attribute control for rule inheritance, but these approaches offer better control:

1. Location Tag Control

<configuration>
    <location path="." inheritInChildApplications="false">
        <system.webServer>
            <rewrite>
                <rules>
                    <rule name="RootOnlyRule">
                        <match url="^([^/]+)/?$" />
                        <action type="Rewrite" url="?id={R:1}" />
                    </rule>
                </rules>
            </rewrite>
        </system.webServer>
    </location>
</configuration>

2. Conditional Pattern Matching

Modify the original rule to include path validation:

<rule name="RootLevelOnly">
    <match url="^([^/]+)/?$" />
    <conditions>
        <add input="{URL}" pattern="^/[^/]+" />
        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
    </conditions>
    <action type="Rewrite" url="?id={R:1}" />
</rule>

For applications with complex directory structures:

<rule name="VirtualDirectoryAwareRule">
    <match url="^([^/]+)/?$" />
    <conditions logicalGrouping="MatchAll">
        <add input="{PATH_INFO}" pattern="^/rootpath(/|$)" />
        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
    </conditions>
    <action type="Rewrite" url="?id={R:1}" />
</rule>

When evaluating solutions, consider:

• Location tags impose minimal overhead
• Pattern-based conditions add marginal processing time
• Rule removal in subdirectories creates additional configuration reads

1. Test rules in development with failed request tracing
2. Verify inheritance behavior in both integrated and classic pipelines
3. Document rule purposes clearly in config comments