Fastly's shielding service feature allows you to designate a specific Point of Presence (POP) as a shield node to your origins. Once designated, all requests to your origin will go through that datacenter, increasing the chances of getting a HIT for a given resource.

However, there are various limitations/requirements to what you can do in the VCL in order to support shielding. It should be investigated if it is possible for our .vcl to comply with these limitations/requirements