Which capability of the network-as-a-service layer uses the philosophy of "never trust, always verify"?

Zero Trust Network Access (ZTNA) is a key component of a Zero Trust architecture, which operates on the principle of 'never trust, always verify.' ZTNA ensures that every user and device is authenticated and authorized before gaining access to applications and resources, regardless of their network location, eliminating implicit trust based on network segmentation.

Software-Defined Wide Area Network (SD-WAN) primarily focuses on optimizing network performance, traffic routing, and management across geographically dispersed locations, not on a security trust model.

Quality of Service (QoS) mechanisms are used to prioritize specific types of network traffic to ensure predictable performance for critical applications, rather than implementing a security trust philosophy.

A Virtual Private Network (VPN) traditionally establishes an encrypted tunnel, and once a user is authenticated to the VPN gateway, they are often implicitly trusted to access the internal network, which contradicts the 'never trust, always verify' principle.