Question

Which of the following facts determines how often a nonroot bridge or switch sends an 802.1D STP Hello BPDU message?

a. The Hello timer as confi gured on that switch.
b. The Hello timer as confi gured on the root switch.
c. It is always every 2 seconds.
d. The switch reacts to BPDUs received from the root switch by sending another BPDU 2 seconds after receiving the root BPDU.

Answer 1

b. The Hello timer as configured on the root switch.

Step-by-step explanation:

There are differrent timers in a switch. The root switch is the only forwarding switch in a network, while non root switches blocks traffic to prevent looping of BPDUs in the network. Since the root switch is the only forwarding switch, all timing configuration comes from or is based on the configuration in the root.

The hello timer is no exception as the nonroot switch only sends 802.1D DTP hello BPDU messages forwarded to it by the root switch and its frequency depends on the root switch hello timer.