The HCIA-Datacom V1.0 Exam (H12-811_V1.0)

Comprehensive Explanation: In STP, the switch with the lowest Bridge ID is selected as the root bridge. The Bridge ID consists of the bridge priority and the MAC address. In this case, the switch with the bridge priority of 4096 has the lowest Bridge ID, making it the root bridge. If two switches have the same bridge priority, the MAC address is used to break the tie, with the lower MAC address winning.

Detailed Explanation:

Probe Request: Sent by the client to detect nearby APs.

Probe Response: Sent by APs in response to the client’s request.

Beacon: Periodically broadcast by APs to announce their presence and SSID. The Discovery packet type does not exist in the 802.11 standard.

(Reference: HCIA-WLAN Training Material, WLAN Packet Types)

To ensure communication between Host A and Host B, we need to analyze the network topology, VLAN configuration, and the role of SWC as an intermediate switch. Let’s break it down step by step, based on VLAN and trunking principles as outlined in HCIA Datacom documentation:

Understanding the Current Network Configuration:

Host A and Host B: Both are connected to SWA and SWB, respectively, via access ports assigned to VLAN 2. Access ports carry untagged traffic for a single VLAN (in this case, VLAN 2), so Host A and Host B are part of VLAN 2.

SWA and SWB Trunk Interfaces: G0/0/1 on SWA and G0/0/2 on SWB are configured as trunk interfaces allowing all VLANs. Trunk ports carry tagged traffic for multiple VLANs (including VLAN 2 in this case) and are used to interconnect switches, enabling VLAN traffic to pass between them. Since these trunk ports allow all VLANs, VLAN 2 traffic can traverse between SWA and SWB.

SWC: SWC is the intermediate switch connecting SWA and SWB via its G0/0/1 (connected to SWA’s G0/0/1) and G0/0/2 (connected to SWB’s G0/0/2). However, the diagram and question do not specify SWC’s current VLAN or port configurations. By default, if no VLAN or trunk configuration exists on SWC, VLAN 2 traffic cannot pass through SWC, preventing communication between Host A and Host B.

Requirements for Communication Between Host A and Host B:

For Host A and Host B (both in VLAN 2) to communicate across the network, VLAN 2 traffic must be able to traverse SWC. This requires:

VLAN 2 to be created on SWC so that the switch recognizes and processes traffic for that VLAN.

The interfaces on SWC (G0/0/1 and G0/0/2) connecting to SWA and SWB must be configured as trunk ports to carry tagged VLAN 2 traffic, matching the trunk configuration on SWA’s G0/0/1 and SWB’s G0/0/2.

Trunk ports are necessary because they can carry traffic for multiple VLANs (tagged) and are typically used between switches to maintain VLAN consistency across the network.

Evaluating Each Option:

A. Create VLAN 2 on SWC.

Creating VLAN 2 on SWC is necessary, but it alone is insufficient. Without configuring the ports (G0/0/1 and G0/0/2) as trunk interfaces allowing VLAN 2, the VLAN traffic cannot pass through SWC. This option is incomplete and incorrect.

B. Configure G0/0/1 on SWC as a trunk interface that allows packets from VLAN 2 to pass through.

Configuring G0/0/1 as a trunk interface allowing VLAN 2 is part of the solution, but it only addresses the connection to SWA. G0/0/2 (connected to SWB) also needs to be configured as a trunk interface allowing VLAN 2 for bidirectional communication between Host A and Host B. This option is incomplete and incorrect.

C. Create VLAN 2 on SWC, and configure G0/0/1 and G0/0/2 as trunk interfaces that allow packets from VLAN 2 to pass through.

This option addresses all requirements:

Creating VLAN 2 on SWC ensures the switch recognizes VLAN 2 traffic.

Configuring both G0/0/1 and G0/0/2 as trunk interfaces allowing VLAN 2 ensures that tagged VLAN 2 traffic can pass between SWA and SWB through SWC, enabling communication between Host A and Host B.

This is the complete and correct solution, aligning with VLAN and trunking principles in HCIA Datacom.

D. On SWC, configure G0/0/1 as a trunk interface that allows packets from VLAN 2 to pass through, configure G0/0/2 as an access interface, and set the PVID to 2.

Configuring G0/0/1 as a trunk interface allowing VLAN 2 is correct for the connection to SWA. However, configuring G0/0/2 as an access interface with PVID 2 (Port VLAN ID) is incorrect for this scenario:

Access ports carry untagged traffic for a single VLAN and are typically used for end devices, not for interconnecting switches. Since SWB’s G0/0/2 is a trunk interface allowing all VLANs, G0/0/2 on SWC must also be a trunk interface to match and carry VLAN 2 traffic.

Using an access port on G0/0/2 would prevent VLAN 2 traffic from passing correctly, as it would expect untagged traffic only for VLAN 2, which conflicts with SWB’s trunk configuration.

This option is incorrect because it mixes access and trunk port types inappropriately for inter-switch links.

Conclusion:

To ensure communication between Host A and Host B (both in VLAN 2), SWC must:

Create VLAN 2.

Configure G0/0/1 and G0/0/2 as trunk interfaces allowing VLAN 2 traffic.

Option C fulfills these requirements, making it the correct answer.

Answer: C

References from HCIA Datacom Documents:

HCIA Datacom V3.0, Chapter 4: VLAN Technologies – Access and Trunk Port Configurations

HCIA Datacom V3.0, Chapter 4: VLAN Trunking and Inter-VLAN Routing – Configuring Trunk Ports for VLAN Traffic

Huawei VLAN Configuration Guide (HCIA Datacom Certification Material) – VLAN Creation and Port Link Types

IPv6 Anycast Address Characteristics:

Option A: True. Packets are delivered to the nearest interface based on routing distance.

Option B: False. Anycast addresses are not designed for load balancing.

Option C: True. Anycast addresses share the same address space as unicast.

Option D: True. Anycast provides redundancy by allowing multiple endpoints to share the same address​​.

Comprehensive Explanation: In RSTP (Rapid Spanning Tree Protocol), the Alternate Port is the backup path to the root bridge. If the current root port fails, the Alternate Port immediately transitions to the forwarding state, providing a new path to the root bridge with minimal delay. This rapid transition is one of the key improvements of RSTP over the older STP protocol. Backup ports, on the other hand, provide redundancy on the same switch, and edge ports are used to connect directly to end devices.

Detailed Explanation:RSTP (Rapid Spanning Tree Protocol) employs a synchronization mechanism with the proposal/agreement handshakes to prevent loops during topology changes. By synchronizing states between switches, RSTP avoids temporary loops while quickly transitioning ports to the forwarding state. (Reference: HCIA-Datacom Training Material, RSTP Mechanisms and Synchronization)

Comprehensive Explanation: The command dot1q termination vid 100 in the configuration specifies that the sub-interface is configured to receive tagged data frames for VLAN 100. VLAN tagging ensures that frames are properly identified and routed through the correct VLAN, and the sub-interface is associated with a specific VLAN ID to handle the tagged traffic.

To help Fit APs locate an AC (Access Controller), the DHCP server must provide the AC IP address using DHCP Option 43.

Option 55 (Incorrect): Used to request a list of DHCP options.

Option 82 (Incorrect): Used for Relay Agent Information, not AC discovery.

Option 10 (Incorrect): Not relevant for APs or CAPWAP.

Option 43 (Correct): This option delivers the AC IP address to Fit APs so they can establish a CAPWAP tunnel.

Thus, the correct answer is D.

Routers can learn routes from various sources:

Static routes: Manually configured routes.

Direct routes: Routes to networks directly connected to the router.

Summary routes: Aggregated routes summarizing multiple networks, often used in routing protocols.

Dynamic routes: Routes learned via routing protocols like OSPF, RIP, or BGP. These sources contribute to the router ' s routing table, enabling it to forward packets to known destinations​.