How can I get a better cache hit ratio?
(1) Set a long enough cache expiry. This can be done in control panel, edit CDN resource, under advance settings > Cache Expiry. Refer more from https://help.onapp.com/hc/en-us/articles/360006903134
(2) Reduce the location being assigned to a resource. Focus on the location where the end users are.
(3) For "hot"/"popular" files, you can prefetch to all edge servers in advance using the prefetch features in control panel (click into a cdn resource)