Finding interface IP and link status Which set of IOS commands will display an interface’s current IP addressing and its Layer 1/Layer 2 status information?
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A1, 2 and 4 (show version; show protocols; show controllers)
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B2, 3 and 5 (show protocols; show interfaces; show ip interface)
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C3 and 4 only (show interfaces; show controllers)
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DNone of the above
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E1, 3 and 5 (show version; show interfaces; show ip interface)
Answer
Correct Answer: 2, 3 and 5 (show protocols; show interfaces; show ip interface)
Explanation
Introduction / Context:Troubleshooting an IOS interface usually begins by confirming the IP address and the basic link state at Layer 1 (physical) and Layer 2 (data link). Multiple IOS commands expose these details from different angles. Knowing which commands provide what information helps you build a quick, repeatable triage flow.
Given Data / Assumptions:
- The candidate commands are: show version; show protocols; show interfaces; show controllers; show ip interface.
- We need to see IP addressing and link state (L1/L2).
- Standard IOS behavior is assumed.
Concept / Approach:
show protocols lists the routed protocols and shows, per interface, whether they are up along with configured IP addresses. show interfaces provides comprehensive per-interface information including line status (up/down), protocol state, errors, and the interface's IP address. show ip interface summarizes IP-specific details (address, helper settings, ACLs) and includes interface status. In contrast, show version focuses on platform information and software, and show controllers provides low-level hardware/controller diagnostics without consistently listing IP addressing.
Step-by-Step Solution:
Use show protocols to confirm configured IP and basic up/down state.Use show interfaces to view L1/L2 status, errors, and the IP line in the output.Use show ip interface to confirm L3 details and operational status.Correlate the outputs to diagnose both addressing and link problems.Verification / Alternative check:
Cross-checking across these three commands ensures accuracy: mismatches often reveal misconfigurations such as shutdown interfaces with IPs configured or ACLs blocking traffic despite link status being up.
Why Other Options Are Wrong:
- Option A: show version does not list interface IPs; show controllers lacks full IP context.
- Option C: omits show protocols or show ip interface, both of which help confirm IP addressing.
- Option D: incorrect because a correct set exists.
- Option E: show version again doesn't show interface IPs.
Common Pitfalls:
- Using only one command and missing a key clue (for example, L1 up but L2 down).
- Misreading cached outputs; always refresh with a new command invocation.
Final Answer:
2, 3 and 5 (show protocols; show interfaces; show ip interface)