Explanation From HCIA-Security documents:

In a PKI, certificate revocation is mainly about requester authentication and approval, not about using one mandatory communication method. The RA is responsible for verifying the applicant’s identity and the legitimacy of the revocation request, then submitting the validated request to the CA. After approval, the CA updates the certificate status, typically by publishing an updated CRL or providing status through OCSP, so relying parties can detect that the certificate is no longer trustworthy.

A “signed and encrypted email” is only one possible way to send a revocation request, but it is not required. In practice, organizations may accept revocation requests through a portal, ticketing system, dedicated PKI management interface, phone with pre-agreed authentication, or other controlled channels. If email is used, digital signature can help prove the requester’s identity and protect integrity, while encryption is optional and depends on policy because the key need is authorization, not confidentiality.

Explanation From HCIA-Security documents:

TCP is a connection-oriented transport protocol, so it must establish a reliable session before user data can be exchanged. To create the session, TCP uses the three-way handshake: the initiator sends a SYN to request a connection and advertise its initial sequence number, the responder replies with SYN/ACK to acknowledge the request and provide its own initial sequence number, and finally the initiator sends an ACK to confirm receipt. This process confirms bidirectional reachability, synchronizes sequence numbers, and prepares both ends for reliable delivery, retransmission control, and flow control.

To end a TCP connection gracefully, TCP performs an orderly close in both directions (full-duplex). One endpoint sends FIN to indicate it has no more data to send, the peer responds with ACK . When the peer is also ready to stop sending, it transmits its own FIN , and the original endpoint responds with a final ACK . Because each direction is closed independently, termination is typically described as a four-way handshake .

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.

Huawei firewalls are stateful devices. This means they do not evaluate every packet only by static rules; instead, they track communications as sessions and then handle subsequent packets based on the session state. When the first packet of a flow arrives, the firewall matches it against the security policy, performs checks (and NAT if configured), and if allowed, it creates a session entry in the session table. That entry records key information such as source/destination IP addresses, protocol, ports or identifiers, zones, NAT translation information, timeout values, and the current state.

After the session is created, later packets of the same TCP/UDP flow, or related ICMP traffic, are forwarded efficiently by querying the session table first. If a matching session exists and the state is valid, the firewall applies the corresponding actions (permit/deny, NAT mapping, logging, QoS, inspection) without repeating the full policy lookup each time. If no session matches, the firewall treats the packet as a new flow and re-evaluates it against policies. Therefore, the statement is true.

Explanation From HCIA-Security documents:

HTTPS protects web-based management by combining encryption with server identity authentication . For the browser to trust the device’s HTTPS service, the device must present a server certificate that can be validated by the browser. That is why administrators often configure the device to use a local certificate (the device’s certificate) that is issued by a trusted CA or whose CA chain has been imported into the browser/OS trust store. When the certificate is trusted, the browser can verify the certificate chain, validity period, and hostname binding, which helps prevent attackers from impersonating the device during login.

If a device uses a self-signed or untrusted certificate, the browser shows warnings and users may click through them, increasing the risk of man-in-the-middle attacks and credential theft. Using a CA-trusted certificate strengthens administrator logins by ensuring the management page you connect to is genuinely the intended device and that the session is encrypted end-to-end.

Explanation From HCIA-Security documents:

In the TCP/IP and OSI reference models, the transport layer is responsible for end-to-end communication between hosts. It provides services such as segmentation, multiplexing through port numbers, and (depending on the protocol) reliability, flow control, and congestion control. The two core transport layer protocols are TCP and UDP.

TCP is connection-oriented and reliable: it establishes a session using the three-way handshake, uses sequence numbers and acknowledgments for retransmission, and supports flow and congestion control to ensure ordered delivery. UDP is connectionless and best-effort: it does not build a session or guarantee delivery, which makes it lightweight and suitable for scenarios such as voice/video streaming and simple query/response services.

By contrast, FTP and DHCP are application layer protocols. FTP provides file transfer services and runs over TCP ports, while DHCP provides dynamic IP address assignment and uses UDP at the transport layer but is itself an application-layer protocol. Therefore, the transport-layer protocols in the options are UDP and TCP.

Explanation From HCIA-Security documents:

The question describes a NAT mode that does two things at the same time:

it translates IP addresses and port numbers (so multiple internal hosts can share one public address), and

it specifically uses the public IP address of the outbound interface as the translated address.

That combination matches Easy IP. Easy IP is essentially a convenient form of source NAT/PAT where the device automatically uses the egress interface’s public IP as the post-NAT source address and differentiates internal sessions by translating source ports. This is widely used when an enterprise has one public IP on the WAN interface and many intranet hosts need Internet access.

NAPT is the general concept of translating both address and port, but it does not inherently require using the outbound interface IP; it can use addresses from a configured public address pool. NAT No-PAT translates only addresses without port translation, so it does not fit. “3-tuple NAT” is not the standard match for the specific “use outbound interface public IP” description. Therefore, the correct answer is Easy IP.