What must be added to an Azure content delivery network to enable token authentication?

To enable token authentication for an Azure Content Delivery Network (CDN), an encryption key is essential. This key plays a crucial role in securing the tokens that validate user access to the content being delivered through the CDN. When token authentication is implemented, the encryption key is used to sign the tokens, ensuring that they are secure and cannot be tampered with. This process enables only authorized users with valid tokens to access the protected content, contributing to enhanced security.

In the context of Azure CDN, enabling token authentication allows for more granular access control, as it ensures that only users with valid tokens, generated using the correct encryption key, have access to specific resources. This makes it an effective method for controlling access to sensitive content delivered over the CDN.

Other options, while relevant to various scenarios in Azure, do not specifically address the need for token authentication in the context of a CDN. For instance, an Access Control List (ACL) primarily manages permissions and access at a different level, while Traffic Manager is geared towards routing and performance optimization. API Management, although it can provide security and access control features, is not directly related to the specific use case of token authentication for CDN content.