HCIA-Security H12-711_V4.0 Full Course Free

Explanation From HCIA-Security documents:

IPsec secures user traffic mainly through the ESP or AH mechanisms, delivering a combination of confidentiality and authentication-related protections. Data encryption (A) provides confidentiality so that intercepted packets cannot be read by unauthorized parties. This is typically delivered by ESP using symmetric encryption algorithms negotiated during IKE.

For authentication, IPsec provides data origin authentication (B) , meaning the receiver can confirm that packets were generated by the expected peer (the holder of the correct IPsec SA and keys). Along with that, IPsec performs a data integrity check (D) so that any modification to the protected portion of a packet in transit is detected; integrity is commonly provided using an HMAC or authenticated encryption method.

Finally, IPsec also includes anti-replay (C) protection. By using sequence numbers and a replay window, the receiver can detect and discard duplicated old packets, which prevents attackers from capturing encrypted/authenticated traffic and retransmitting it to disrupt sessions or attempt misuse.

Because IPsec secure transmission depends on encryption plus authentication, integrity, and replay protection working together, all four options are correct.

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.