I'm using the standard microsoft CDN in front of an Azure Storage Static website.
The origin doesn't respond with any cache headers (not supported by Static Website), but I have configured in my endpoint rules engine with the following.
"Then 'Cache Expiration', Override, 90 days", which at least appears to set the cache-control header in the CDN response.
From the docs I've read, this 'Cache Expiration' setting should also inform the CDN POP to cache for 90 days. However, while testing I have noticed that in visits after 1 day, about 30% of requests are served as 'TCP_REMOTE_HIT' and another 30% as 'TCP_MISS'.
Is the setting for Cache Expiration correct, to specify the cache expiration at the POPs? Or is there some other reason for such quick evacuation of the cache at the POPs.