While both caching mechanisms serve similar purposes, their architectural implementations differ significantly:

// ASP.NET Output Cache declaration in Web.config
<caching>
  <outputCacheSettings>
    <outputCacheProfiles>
      <add name="ProductCache" duration="3600" varyByParam="id" />
    </outputCacheProfiles>
  </outputCacheSettings>
</caching>

// IIS Output Cache declaration in applicationHost.config
<system.webServer>
  <caching>
    <profiles>
      <add extension=".aspx" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" />
    </profiles>
  </caching>
</system.webServer>

The statement about ASP.NET's content-type flexibility refers to its ability to cache non-HTML responses:

// Caching JSON response in ASP.NET MVC
[OutputCache(Duration=300, VaryByParam="none")]
public ActionResult GetProductData(int id)
{
    return Json(products.Get(id), JsonRequestBehavior.AllowGet);
}

// Caching XML response
[OutputCache(Duration=600, VaryByParam="id")]
public XmlResult GetProductSpecs(int id)
{
    return new XmlResult(products.GetSpecs(id));
}

• Static content with no dynamic processing
• High-traffic scenarios where kernel-mode caching improves performance
• When you need to cache at the web server level without .NET involvement
• For non-ASP.NET content (HTML, images, CSS)

• Dynamic ASP.NET pages with personalized content
• When you need programmatic control over cache invalidation
• For API responses (JSON/XML) requiring cache duration control
• When using cache dependencies (SQL, file, etc.)

Combining both caches for optimal performance:

// Controller action with both ASP.NET and IIS caching
[OutputCache(
    Duration = 1800,
    VaryByParam = "id;culture",
    Location = OutputCacheLocation.Server)]
public ActionResult ProductDetail(int id, string culture)
{
    // IIS will cache the final rendered output
    Response.Cache.SetOmitVaryStar(true);
    Response.Cache.SetCacheability(HttpCacheability.Public);
    Response.Cache.SetExpires(DateTime.Now.AddMinutes(30));
    
    return View(products.GetLocalized(id, culture));
}

Benchmark results from a typical e-commerce page:

When working with ASP.NET applications in IIS, you have two distinct caching mechanisms at your disposal:

// ASP.NET Output Cache declaration
[OutputCache(Duration=3600, VaryByParam="id")]
public ActionResult ProductDetail(int id)
{
    // Controller logic
}

The IIS output cache operates at a lower level in the request pipeline and is configured through web.config:

<system.webServer>
    <caching>
        <profiles>
            <add extension=".aspx" policy="CacheUntilChange" kernelCachePolicy="CacheUntilChange" />
        </profiles>
    </caching>
</system.webServer>

ASP.NET's output cache can handle any content type (HTML, JSON, XML, etc.) when using Integrated Pipeline mode. For example:

[OutputCache(Duration=60, VaryByParam="none")]
public JsonResult GetLatestStats()
{
    return Json(new { metrics = GetMetrics() }, JsonRequestBehavior.AllowGet);
}

IIS Output Cache is better when:
- You need kernel-mode caching for static content
- Caching entire file types (like .css or .js)
- You want caching without ASP.NET involvement

ASP.NET Output Cache excels when:
- You need dynamic content caching (like user-specific pages)
- Want programmatic control (VaryByCustom, VaryByHeader)
- Need to cache non-HTML responses

For maximum performance, combine both caches strategically:

<system.web>
    <caching>
        <outputCacheSettings>
            <outputCacheProfiles>
                <add name="ProductCache" duration="3600" varyByParam="id" />
            </outputCacheProfiles>
        </outputCacheSettings>
    </caching>
</system.web>

<system.webServer>
    <caching>
        <profiles>
            <add extension=".aspx" policy="CacheForTimePeriod" duration="00:30:00" />
        </profiles>
    </caching>
</system.webServer>

Test scenarios show:

• IIS cache: ~5,000 RPS for static content
• ASP.NET cache: ~3,200 RPS for dynamic pages
• Combined: ~4,100 RPS for hybrid scenarios

Remember to monitor with:

appcmd list cache
// and
System.Web.Caching.Cache.GetStats()