Which three items do you recommend for control plane hardening of an infrastructure device?

Control plane hardening is a critical aspect of securing infrastructure devices. Recommended measures include:

A. Routing protocol authentication: Prevents unauthorized devices from injecting false routes by requiring secure key-based authentication (e.g., MD5 or SHA for OSPF/BGP).

B. SNMPv3: Provides secure management through authentication and encryption, preventing interception or modification of SNMP traffic.

C. Control Plane Policing (CoPP): Enforces rate limits and filtering for traffic directed to the device's CPU, protecting against DoS and control plane overloads.

Why other options are incorrect:

D. Redundant AAA servers support authentication resilience but are more about access control than direct control plane protection.

E. Warning banners are a legal and administrative best practice, not a technical control plane defense.

F. Enabling unused services is the opposite of best practices and increases the attack surface.

These control-plane protections are emphasized in CCDE v3.1 design guidance for resilient and secure infrastructure designs.