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Enable HTTP compression (Static and Dynamic) in Internet Information Service (IIS) Manager

Nov 1, 2021

HTTP compression used to compress HTTP content and responses output by the server. This feature used to compress HTML, JavaScript, JSON, Image, etc.

There are two types of compression

Static Compression: Compress static contents such as HTML, TEXT, etc. Compressed files cached into the cache directory. Static compression enabled by default.
Dynamic Compression: Compress dynamic content such as JSON, JavaScript that created according to the client’s request. Compressed files not cached into disk and Compress happen each time client sends the request. Therefore, Dynamic Compression required CPU resources to compress the content in real-time

Static compression is installed by default when installing Web Server. But dynamic compression should be enabled manually.

Install Dynamic Compression

Open Server Manager.
In Server Manager, click the Manage menu, and then click Add Roles and Features.
In the Add Roles and Features wizard, click Next. Select Role-based or feature-based installation and click Next.
Select the destination server and click Next.
On the Server Roles page, expand Web Server (IIS), then expand Web Server, expand Performance, and then select Dynamic Content Compression. Click Next.

If enable Static content compression, select whether to compress all files or files larger than specified file size.
If enable Static content compression, select the cache directory path.
If enable Static content compression, select maximum cache size allocated per application pool.
Then Apply to save the configuration.

After that, we need to configure what are the HTTP content should be compressed.

Go to “C:WindowsSystem32inetsrvconfig”
Open applicationHost.config with a text editor
Go to “<httpCompression>” element
Add missing content HTTP types that want to compress under dynamicTypes and staticTypes

Then go to “<serverRuntime>” element And add frequentHitThreshold and frequentHitTimePeriod attributes. In order to compress, number of frequentHitThreshold, request should happen within the frequentHitTimePeriod.
- frequentHitThreshold: Specifies the number of times a URL must be requested, within the period specified in the frequentHitTimePeriod attribute, to be considered frequently hit. The value must be between 1 and 2147483647. The default value is 2.
- frequentHitTimePeriod: Specifies the time interval in which a URL must be requested the number of times specified in the frequentHitThreshold attribute before it is considered to be frequently hit. The default value is 00:00:10 (10 seconds).