The Palo Alto Networks External Dynamic List (EDL) Hosting Service is a cloud-based solution that allows customers to maintain and host their own custom EDLs. According to official documentation, this service is available for use on all supported Palo Alto Networks next-generation firewalls and Prisma Access instances. While a minimum PAN-OS version is required and the service is free with a support contract, option A provides the most accurate and comprehensive description of the platforms on which the service can be deployed, which is a primary requirement.

B. an additional subscription free of charge: The service is not an "additional subscription." It is a feature available to all customers who have a valid, standard support account.

C. a firewall device running with a minimum version of PAN-OS 10.1: This statement is factually correct but incomplete. It omits Prisma Access, which is also a supported platform for the EDL Hosting Service.

D. an additional paid subscription: This is incorrect. The EDL Hosting Service is provided free of charge to customers with a valid support account.

1. Palo Alto Networks. (2023). PAN-OS® Administrator’s Guide Version 11.0. "Objects > External Dynamic Lists > External Dynamic List Hosting Service". The guide states

"The EDL Hosting Service is available for all supported Palo Alto Networks firewalls and Prisma Access." It also clarifies

"The EDL Hosting Service is available free of charge to all Palo Alto Networks customers with a valid support account."

2. Palo Alto Networks. (2021). PAN-OS® New Features Guide Version 10.1. "Policy > External Dynamic List Hosting Service". This document confirms the feature's introduction: "The External Dynamic List (EDL) Hosting service is a new cloud-based solution...This feature is introduced in PAN-OS 10.1." This supports the fact that option C is a valid but incomplete requirement.