Finding a LAN’s broadcast address from user EXEC: From user mode on a Cisco router, which command will display the broadcast address used on a connected LAN interface along with other interface details?

Introduction / Context:
When validating IP addressing on a LAN, you may need to confirm the broadcast address computed from the interface’s IP and mask. IOS includes this information in the detailed interface output. Selecting the right show command ensures you see the operational parameters and layer-3 details for the interface in question.

Given Data / Assumptions:

• We are at user EXEC mode (Router>), where many show commands are allowed.
• We want to view a field explicitly showing the broadcast address.
• We need per-interface operational details, not just configuration lines.

Concept / Approach:

show interfaces displays a comprehensive block per interface that includes IP address, subnet mask, and the derived broadcast address. While show protocols summarizes IP addressing state, the detailed broadcast line consistently appears in the interface-specific output, making show interfaces the most reliable choice for this task.

Step-by-Step Solution:

Verification / Alternative check:

Compute the broadcast address manually from IP/mask and confirm it matches the value reported by IOS, ensuring correctness of the configured subnet.

Why Other Options Are Wrong:

show running-config and show startup-config list configuration but often omit computed broadcast fields.

show protocols offers a brief summary and may not display the broadcast address as explicitly as show interfaces.

Common Pitfalls:

Confusing user EXEC versus privileged EXEC availability; neglecting to check the specific interface when multiple LANs exist; relying on outdated cached values after recent changes—always verify live output.

Final Answer:

show interfaces