Question 1

As shown in the figure, SWA, SWB, and SWC run the Rapid Spanning Tree Protocol (RSTP). What are the roles of SWB's GE0/0/2 and SWC's GE0/0/1?

ABackup port, alternative port

BAlternative port, backup port

CBackup port, root port

DRoot port, designated port

Answer : D

In the topology, SWB's GE0/0/2 is the Root Port because it has the least cost path to the Root Bridge (SWA). SWC's GE0/0/1 is the Designated Port because it forwards traffic to SWA while maintaining the shortest path to the Root Bridge. This setup ensures efficient traffic flow in the spanning tree topology .

Question 2

On a network, some switches are enabled with RSTP and some switches are enabled with STP. What will happen?

AA Huawei switch changes from RSTP to STP. After the STP-enabled switch is removed from the network, the RSTP-enabled switch can be moved back to the RSTP mode.

BA Huawei switch changes its mode from STP to RSTP. After the RSTP-enabled switch is removed from the network, the STP-enabled switch can be moved back to the RSTP mode.

CSTP and RSTP are compatible with each other, but the rapid convergence of RSTP is unavailable.

DSTP and RSTP calculation are performed independently.

Answer : A, C

When STP and RSTP coexist in a network, RSTP switches will downgrade their operation to STP to ensure compatibility. However, this disables RSTP's rapid convergence features, as the protocol behaves like STP to maintain interoperability .

Question 3

Which of the following statements about stack split is false?

AAfter a stack splits, the MAC addresses of the two stacks change immediately.

BIf the master and standby switches are still in the same stack after the stack splits, the slave switches separated from the original master and standby switches re-elect the master and standby switches due to protocol packet timeout.

CIf the master and standby switches are in two stacks after the split, the stack where the original master switch resides updates the topology and selects a new standby switch. The original standby switch becomes the master switch in the new stack and a new standby switch is elected.

DAfter a stack splits, multiple stacks have the same IP address and MAC address. To prevent network faults, the stacks perform MAD detection. The stack that fails the MAD detection shuts down all physical ports except reserved ports.

Answer : A

When a stack splits, the MAC addresses of the newly formed stacks do not change immediately. Instead, they retain their original MAC addresses until new ones are reassigned during topology updates. This delayed update prevents immediate conflicts and allows MAD (Multiple Active Detection) to handle any resulting issues .

Question 4

In PIM-DM, which of the following processes are involved in SPT establishment?

APrune

BGraft

CFlooding

DState-refresh

Answer : A, B, C

In PIM-DM (Protocol Independent Multicast - Dense Mode), the SPT (Shortest Path Tree) establishment process involves flooding to propagate multicast traffic across the network, prune messages to stop sending multicast traffic to unwanted interfaces, and graft messages to re-establish forwarding when needed. State-refresh is not directly involved in SPT establishment but helps maintain the prune state .

Question 5

Which of the following statements regarding multicast MAC addresses are false?

AOne multicast MAC address maps to 32 multicast IP addresses.

BOne multicast MAC address maps to only one multicast IP address.

CThe high 24 bits of the multicast MAC address are 0x01005E, the 25th bit is fixed to 1, and the lower 23 bits of the MAC address map to the lower 23 bits of the multicast IP address.

DA multicast MAC address identifies receivers of a multicast group on the data link layer.

Answer : B

One multicast MAC address maps to 32 multicast IP addresses due to the limited number of bits used in the mapping process. Specifically, the lower 23 bits of the MAC address map to the lower 23 bits of the multicast IP address, while the high 24 bits of the MAC address are fixed as 0x01005E. Thus, Option B is false .

Free Practice Questions for Huawei H12-821_V1.0 Exam

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