Answer A,E is correct: A. They alleviate the shortage of public IPv4 addressses.; E. They provide a layer of security from Internet threats.. Security questions in CCNA 200-301 v1.1 require matching the control to the threat or access requirement. Authentication proves identity, authorization controls what the user can do, and accounting records activity. Firewalls inspect and permit or deny traffic based on policy, while ACLs match packet fields in a defined order. VPN and IPsec questions require knowing whether the design protects unicast traffic, supports tunneling, or encrypts the original packet. Password and SSH questions depend on IOS behavior, including encrypted secrets, local users, domain names, and cryptographic images. The incorrect choices often use a valid technology in the wrong role or provide weaker protection. The selected answer is the Cisco-consistent control because it directly satisfies the access, confidentiality, or threat-mitigation requirement stated in the question.