Clarify Azure Front Door's default caching behaviour in PoP

[Masahigo]

Hi,

I have been going through the following 101 quickstart example:
https://github.com/Azure/terraform/tree/master/quickstart/101-front-door-premium-storage-blobs-private-link

In my project we have a similar setup where we serve a single-page app (SPA) through Azure Front Door (Standard/Premium) from storage account.

But what caught my attention is the default caching suggested by the diagram and data flow description (steps 3 & 6).

The Terraform resource that manages caching is azurerm_cdn_frontdoor_route and the documentation states that if the cache block is not defined in the resource the built-in cache in Azure Front Door should be disabled for the route.

My question: is there some level of default caching taking place in Azure Front Door even if the cache block is not defined for a route in Azure Front Door? And if this really is so could be made more clear in the 101 example as well as in Terraform azurerm documentation?