H12-711_V4.0 Exam Dumps - HCIA-Security V4.0 Exam

Explanation From HCIA-Security documents:

IKE-based SA establishment is designed to automate IPsec parameter negotiation and key management, which makes it especially suitable for environments where configuring many tunnels manually would be inefficient. That is why B is correct: IKE scales better for medium and large networks because it negotiates policies, authenticates peers, and builds SAs dynamically instead of relying on fixed, manually configured keys.

A is incorrect because Security Associations have lifetimes. Both IKE SAs and IPsec SAs are created with time-based and/or traffic-based lifetimes and must be refreshed or renegotiated when they expire to maintain security. Permanent SAs would increase risk because long-lived keys are more exposed to compromise.

C is correct : SPI is a 32-bit identifier used by the receiver to find the correct SA for inbound traffic, and it is typically chosen by the receiving side in a way that avoids collisions—commonly treated as randomly generated in foundational descriptions.

D is correct because IKE uses Diffie-Hellman to derive shared keying material securely over an untrusted network, and then refreshes keys by rekeying based on SA lifetime, achieving dynamic updates.

Explanation From HCIA-Security documents:

AAA provides a unified framework for Authentication, Authorization, and Accounting, and on Huawei devices the AAA authentication method can be selected according to the management and deployment requirements. Local authentication uses user accounts stored on the device itself, which is suitable for small environments, emergency access, or when external servers are unavailable. RADIUS authentication relies on a centralized RADIUS server, commonly used for large-scale user access control and unified credential management. HWTACACS authentication is another centralized mode that supports fine-grained control and is often preferred in scenarios requiring stronger separation of authentication and authorization, as well as detailed command-level management in some deployments. In addition, AAA can be configured for no authentication (also called none), meaning the device does not verify user identity for a specific access scenario. This mode is typically used only in controlled environments or for specific services where authentication is handled elsewhere, because it reduces security. Therefore, all listed modes are supported by AAA.

Application-layer protocols provide network services directly to user applications and define how clients and servers exchange application data. DNS is an application-layer protocol used to translate domain names into IP addresses (and perform related record lookups), enabling applications to locate services by name instead of by numeric address. Telnet is also an application-layer protocol that provides remote terminal access; it allows a user to interact with a remote system’s command-line interface over the network (though it is insecure because it transmits data in plaintext). HTTP is an application-layer protocol used for web communication, defining request/response behavior between browsers (clients) and web servers for transferring web pages and related content.

In contrast, ARP is not an application-layer protocol. ARP operates at the boundary of Layer 2/Layer 3 to map an IPv4 address to a MAC address on the local network segment, supporting frame delivery on Ethernet. Therefore, the application-layer protocols here are DNS, Telnet, and HTTP.

Explanation From HCIA-Security documents:

3-tuple NAT is used to publish internal services to external users by translating destination IP address, destination port, and protocol so that an Internet user can reach an intranet server using a public address and specific service port. So the first part of the statement about enabling proactive external access through translated addresses and ports matches what 3-tuple NAT is used for.

However, NAT translation and firewall access control are two different functions. NAT only defines how addresses and ports are translated; it does not replace the firewall’s security policy decision. On a Huawei firewall, whether a packet is allowed to pass is determined by the configured security policy (interzone policy). If no relevant security policy exists to permit the traffic from the external zone to the internal zone and the mapped service, the firewall will not automatically allow it just because a NAT mapping is present.

Therefore, without an appropriate permit security policy, the access packets will be denied even if 3-tuple NAT is configured.