Key points to remember for the 400-251: CCIE Security written exam.

C.

Storm Control is a feature that is implemented on switches to prevent the flooding of broadcast, multicast, or unknown unicast traffic. This feature allows a switch to monitor traffic levels on an interface and take action when traffic levels exceed a configured threshold. When traffic levels exceed the configured threshold, the switch can either drop or rate-limit traffic, preventing a potential network disruption.

Based on the given answers, we can identify the correct statement as follows:

A. Storm Control does not prevent disruption due to unicast traffic. This statement is true. Storm Control is designed to prevent the disruption of broadcast, multicast, or unknown unicast traffic. However, it does not prevent disruption due to unicast traffic, as this traffic is intended for a specific destination.

B. Storm Control is implemented as a global configuration. This statement is false. Storm Control is implemented on a per-interface basis, allowing administrators to configure different thresholds for different interfaces.

C. Storm Control uses the bandwidth and rate at which a packet is received to measure the activity. This statement is true. Storm Control measures the activity based on the bandwidth and rate at which a packet is received.

D. Storm Control uses the bandwidth and rate at which a packet is dispatched to measure the activity. This statement is false. Storm Control measures the activity based on the bandwidth and rate at which a packet is received, not dispatched.

E. Storm Control is enabled by default. This statement is false. Storm Control is not enabled by default and must be explicitly configured by the network administrator.

In conclusion, the correct statement about Storm Control implementation on a switch is C. Storm Control uses the bandwidth and rate at which a packet is received to measure the activity.