Comprehensive and Detailed In-Depth Explanation:

Wireless LAN (WLAN) roaming allows mobile devices (STAs) to move seamlessly between different APs without dropping connections.

Types of WLAN Roaming:

Layer 2 roaming → STAs move between APs in the same subnet without IP address changes.

Layer 3 roaming → STAs move across different subnets, requiring IP address reconfiguration (handled via DHCP or tunneling).

Since roaming prevents service interruption in large WLAN deployments, the statement is true.

???? Reference: Huawei HCIA-Datacom Study Guide, WLAN Roaming and Seamless Connectivity.

By default, Huawei firewalls create security zones named untrust, dmz, trust, and local. These zones facilitate security policies for inbound, outbound, and inter-zone traffic control ​.

Intra-area route calculation in OSPF involves only Router LSAs (Type 1) and Network LSAs (Type 2). Summary LSAs (Type 3) are used for inter-area routes and do not participate in intra-area route calculation. Therefore, the statement is false ​.

The monitoring plane's primary role is environmental monitoring, ensuring the stability of the system. Functions like voltage monitoring, temperature tracking, fan speed control, and power management are standard. These are independent of the forwarding or control planes and critical for maintaining device health in network operations ​.

The command output indicates that the OSPF neighbor state is Full and that the neighbor relationship has been established. The statement confirms that the negotiation process during the exchange of DD (Database Description) packets has determined the role of the router, with the local device becoming the slave in the Master-Slave relationship, which is critical for LSA synchronization. The other options do not align with the output or OSPF principles ​

In asynchronous mode, two devices exchange BFD Control packets to monitor connectivity. However, this mode does support the echo function, which tests bidirectional paths by sending packets that loop back to the origin. This statement is incorrect. Demand mode, on the other hand, minimizes the control packet exchange, relying on periodic echo packets if configured. Huawei's BFD configuration guides emphasize these distinctions ​.

In an OSPF broadcast or NBMA network with at least two routers, one router must act as the DR (Designated Router), and another as the BDR (Backup Designated Router) to ensure efficient communication and reduce the number of adjacencies. This is a requirement for OSPF operation in such network types ​.

In VRRP HSB (Hot Standby Backup) mode for WLAN deployments (typically between ACs or access controllers), backup of critical data ensures fast failover and minimal service disruption.

A. Real-time backup – Supported. Configuration and session information are synchronized in real-time between the active and standby ACs.

B. Scheduled synchronization – Not supported. HSB requires instant synchronization, not based on a scheduled time.

C. Batch backup – Supported. Some types of less time-sensitive data (e.g., logs or counters) may be backed up in batches.

D. Cloud backup – Not part of HSB functionality. Cloud backup is a separate mechanism, typically used for archival purposes, not real-time failover.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“VRRP HSB mode supports real-time and batch backup between ACs to protect WLAN services. Scheduled and cloud backups are not part of HSB functionality.”

(Chapter: WLAN Reliability – Section: AC Redundancy and HSB Mechanism)