Cloudinary supports delivery of all images both through HTTP and HTTPS (SSL). Cloudinary delivers all images and transformed images through a fast CDN (Akamai, Fastly, and Amazon CloudFront). For HTTP delivery http://res.cloudinary.com is used, for HTTPS the base URL is https://res.cloudinary.com.
If you have an Advanced Cloudinary account with a dedicated CDN distribution, a different domain name might be used for HTTPS.
If you use one of our client libraries (Ruby, PHP, etc.), the URLs of images are built automatically using the correct domain either by detecting the request's protocol or by specifying :secure => true in calls to methods like cl_image_tag and cloudinary_url.