Gzip is a method of data compression when a file is divided into small chunks and each of them is compressed to reduce the overall file size. When files are downloaded they are automatically unzipped so the end user receives the original file without packet loss. Typically, Gzip compression reduces file size by 70% and can be as high as 90%.
Origin supports Gzip Compression
Two versions of a content (compressed and uncompressed) are stored in CDN. While processing a request from end users, CDN servers check if the Accept-Encoding HTTP header contains gzip or deflate, which means that the browser can process compressed content. In this case, a compressed version of the HTTP object will be sent to the end user. If there are no such directives, a CDN will deliver an uncompressed version of a file.
Origin doesn’t support GZIP Compression
Only uncompressed version of the content is stored in CDN. Regardless of how the content is requested, CDN will serve uncompressed files from cache.
Filetypes which can be compressed
How to enable Gzip compression on origin
You can configure Gzip support on your origin. It’s convenient because you can set your own compression preferences for different types of content.
Header append Vary User-Agent
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4\.0 no-gzip
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|pdf|swf|ico|zip|ttf|eot|svg)$ no-gzip
#Optionally, GZip level of compression can be added to the NginX server block using the following directive:
gzip_disable "MSIE [1-6]\.";
How to enable Gzip compression on CDN
You can enable gzip compression directly on CDN Edge servers. In this case, CDN will always request uncompressed content from your origin and compress it on the CDN’s side.
Please follow this manual to enable Compression on CDN.