What is the first step STP performs to establish a loop-free spanning tree in a switched network?

A. Elects a root switch

B. Disables redundant loops in the tree

C. Sets a priority for each redundant link

D. Selects a designated switch for each switched segment








 

Suggested Answer: A

The first step taken by the Spanning-Tree Protocol (STP) is to elect a root bridge (switch). The root bridge keeps the STP database. The bridge ID is used to select the root bridge in the network. The bridge ID is a combination of the priority of the bridge (switch) and the MAC address. If two switches or bridges have the same priority value, the switch with the lowest MAC address will have the lowest priority and become the root bridge.
Once the STP process is complete (after switches go through the learning and listening stages), STP disables redundant loops in the network.
STP does not set a priority for each redundant link. The network administrator can manually set the priority of a switch. STP then uses the priority and the switch's
MAC address to calculate the bridge ID, which is used to select the root bridge.
STP does not first select a designated switch for each switched segment. The first goal of STP is to select a root bridge for a switched segment (VLAN).
Objective:
Layer 2 Technologies -
Sub-Objective:
Configure and verify spanning tree
References:
Catalyst 6500 Release 12.2SXF and Rebuilds Software Configuration Guide > Configuring STP and IEEE 802.1s MST > Creating the Spanning Tree Topology
Cisco > Support > Configuring Spanning Tree Protocol > How STP Works

This question is in 300-115 Implementing Cisco IP Switched Networks (SWITCH) Exam
For getting Cisco Certified Network Professional (CCNP) Routing and Switching Certificate





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