Which two options are requirements for EIGRP authentication? (Choose two)

Crypto maps are primarily used for configuring IPsec VPNs, which is a different security mechanism and not a requirement for EIGRP's native routing protocol authentication.

EIGRP authentication is configured and applied on a per-interface basis, specifically using commands like ip authentication key-chain eigrp and ip authentication mode eigrp under the interface configuration to specify the authentication parameters.

EIGRP authentication keys (or keychains) are applied to specific interfaces where EIGRP runs, not configured directly within the global EIGRP routing process configuration.

For successful EIGRP neighbor authentication and adjacency establishment, the active key ID, the key string, and the authentication algorithm must all match precisely between the two neighboring routers.

While a key chain is typically configured to define and manage authentication keys, the question asks for two specific requirements for authentication to work, and B and D are more direct operational conditions.

An IPsec profile is used for IPsec VPNs, which provides a different layer of security (Layer 3 encryption and authentication) and is not a requirement for EIGRP routing protocol authentication.