You can whitelist specific domains in order to allow only specific external sources to be requested. In addition, you can combine Domain whitelisting with Aliases above to send custom headers to an non-public external storage for authentication purposes.
In order to whitelist a specific domain, you need to enter the domain name without https://
Here, domain sample.li is whitelisted. Which means that if we try to process an image with any other domain except sample.li (eg: www.your-own-domain.com), it will return a HTTP 406 (Not acceptable) error.
However, this response can be changed to HTTP 404 (Default missing image)
