Which feature is used to restrict communication between interfaces on a Cisco ASA?

VLAN subinterfaces are a method for segmenting a single physical interface into multiple logical interfaces, but they don't inherently restrict communication between them without additional security policies.

Traffic zones are a concept primarily associated with Cisco IOS Zone-Based Firewalls (ZFW), not the Cisco ASA platform.

VxLAN interfaces are used for overlay networking in data centers to extend Layer 2 segments over a Layer 3 network, and are not a feature for restricting communication between interfaces on a Cisco ASA.

Cisco ASA firewalls use security levels, numerical values (0-100), assigned to interfaces to control traffic flow. By default, traffic is permitted from a higher security-level interface to a lower security-level interface, while traffic from a lower to a higher security-level interface is denied, providing a fundamental restriction on communication between interfaces.