Comprehensive and Detailed Explanation:
* IKEv1 Phase 1 (Main Mode) consists of six messages:
* Messages 1 & 2 # Negotiate security proposals(encryption, authentication, and DH group).
* Messages 3 & 4 # Exchange key-related information.
* Messages 5 & 6 # Perform mutual authentication.
* Why is B correct?
* Messages 1 and 2 negotiate IKE proposalsbetween VPN peers.
HCIP-Security References:
* Huawei HCIP-Security Guide # IKEv1 Main Mode Negotiation

Comprehensive and Detailed Explanation:
* DoS (Denial-of-Service)# A single attacker sends excessive traffic to a target.
* DDoS (Distributed Denial-of-Service)# Uses multiple compromised devices (zombies or botnets) to amplify the attack.
* Why is this statement true?
* DDoS attacks originate from multiple sources (botnets), unlike DoS attacks.
HCIP-Security References:
* Huawei HCIP-Security Guide # DoS vs. DDoS Attacks

Comprehensive and Detailed Explanation:
* Heartbeat linksbetween firewalls ensuresynchronization and failover.
* Layer 2 or Layer 3 configuration depends on deployment needs, but there isno strict 30% bandwidth rulefor Eth-Trunk heartbeat links.
* Why is this statement false?
* The30% threshold condition is incorrect.
* Eth-Trunk heartbeat links aretypically Layer 3 for better failover and routing control.
HCIP-Security References:
* Huawei HCIP-Security Guide # Firewall High Availability Deployment

Explanation:
Intrusion Prevention Systems (IPS) in firewalls follow amulti-step processto detect and mitigate threats. The steps occur in a logical sequence:
1##Step 1: Identifies and Parses Application-Layer Protocols
* The firewall firstidentifies the protocol being used(e.g., HTTP, FTP, DNS, SMTP).
* Parsing the protocol helps the IPS engineunderstand how the data is structuredand what types of attacks might be embedded.
* This step is crucial for detectingprotocol-based attackslike SQL injection or cross-site scripting (XSS).
2##Step 2: Reassembles IP Fragments and TCP Flows
* Attackers oftensplit malicious payloads across multiple packetsto evade detection.
* The firewallreassembles fragmented packets and TCP flowsto reconstruct the full data stream.
* This step is critical for detectingevasion techniques such as fragmented attacks or out-of-order packet attacks.
3##Step 3: Performs Signature Matching
* Once the full data stream is reassembled, the IPScompares it against known attack signatures.
* Signature matching helps detect:
* Malware patterns(e.g., botnets, Trojans).
* Exploits targeting vulnerabilitiesin software and operating systems.
* Firewalls usepredefined signature databasesthat are regularly updated.
4##Step 4: Performs the Response Action Based on the IPS Profile
* If an attack is detected, the firewall takes anaction based on the IPS policy:
* Block the traffic(drop malicious packets).
* Alert the administrator(generate logs and alerts).
* Rate-limit traffic(slow down potential attack sources).
* Theresponse mechanism is customizablebased on security requirements.

Comprehensive and Detailed Explanation:
* Threshold settings in firewalls allow administrators to define:
* Alarm threshold# When exceeded, logs are generated.
* Block threshold# When exceeded, the action is blocked.
* Why is B false?
* The alarm threshold does not block traffic; it only generates logs.
* Only the block threshold enforces blocking actions.
HCIP-Security References:
* Huawei HCIP-Security Guide # HTTP Traffic Control