Last Updated: January 28, 2019
Create robots-cdn in CDN Sun (https://cdnsun.com/)
1. Create robots-cdn.txt file on the root directory
Add the following code
User-agent: * Allow: /wp-content/* Disallow: /
2. On your site .htaccess add the following
RewriteEngine On
SetEnvIf X-Resource "#########" IS_CDNSUN_REQUEST="yes"
RewriteCond %{ENV:IS_CDNSUN_REQUEST} "yes"
RewriteRule "robots.txt" "robots-cdn.txt" [L]
### = resource can be found at CDN Sun dashboard
3. on CDN sun service setting, disable block crawlers
https://cdnsun.com/cdn/settings
Block Crawlers: disable
References
https://cdnsun.com/knowledgebase/cdn-static/setting-a-block-crawlers-avoid-duplicate-content-seo