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<p>When a page is being served via HTTPS and the CDN does not support HTTPS, then the file will not be served from the CDN, because it would make the visit insecure.</p>
<p>If your CDN does support HTTPS, and if you are not masking the original URL's domain with another (sub)domain (using a CNAME record), enable the corresponding setting below, and your CDN will also be used on HTTPS pages.</p>