Cisco CCNA mock exam questions sample test – Question 109

.Two catalyst switches on a LAN are connected to each other with redundant links and have Spanning Tree Protocol (STP) disabled.
What problem could occur from this configuration?

A. It may cause broadcast storms.
B. All ports on both switches may change to a forwarding state.
C. It may cause a collision storm.
D. These switches will not forward VTP information.

Correct Answer: A

The configuration in the scenario may cause broadcast storms. When there are redundant links between two switches, it is recommended that you enable Spanning Tree Protocol to
avoid switching loops or broadcast storms. Loops occur when there is more than one path between two switches. STP allows only one active path at a time, thus preventing loops. A
broadcast storm occurs when the network is plagued with constant broadcasts. When the switches have redundant links, the resulting loops would generate more broadcasts,
eventually resulting in a complete blockage of available bandwidth that could bring the complete network down. This situation is referred to as a broadcast storm.
The option stating that all ports on both switches may change to a forwarding state is incorrect. Forwarding is a port state that is available when using STP. When STP is disabled, the
switch cannot change the STP states of its ports.
The option stating that the switches will not forward VLAN Trunking Protocol (VTP) information is incorrect. Enabling or disabling STP does not have a direct effect on VTP messages.
The term collision storm is not a valid term.
LAN Switching Fundamentals
Configure, verify, and troubleshoot interswitch connectivity
Cisco > Support > Technology Support > LAN Switching > Ethernet > Design > Troubleshooting LAN Switching Environments > Document ID: 12006 > Spanning Tree Protocol