This JNCIA-JUNOS practice question tests your understanding of user interfaces. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An administrator is troubleshooting an interface and wants to see real-time packet statistics. Which command should they use?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
traceoptions
Why wrong: traceoptions is used for debugging protocols, not for real-time interface stats.
show interfaces statistics
Why wrong: This shows a snapshot, not dynamic updates.
show interfaces extensive
Why wrong: This shows static statistics, not real-time updates.
monitor interface
monitor interface displays real-time interface statistics.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
monitor interface
The 'monitor interface' command in Junos provides real-time, continuously updated packet statistics for a specified interface, making it the correct choice for live troubleshooting. Unlike static commands, it refreshes statistics every second until interrupted, allowing the administrator to observe traffic patterns as they occur.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
traceoptions
Why it's wrong here
traceoptions is used for debugging protocols, not for real-time interface stats.
show interfaces statistics
Why it's wrong here
This shows a snapshot, not dynamic updates.
show interfaces extensive
Why it's wrong here
This shows static statistics, not real-time updates.
monitor interface
Why this is correct
monitor interface displays real-time interface statistics.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse 'show interfaces statistics' (a static snapshot) with real-time monitoring, failing to recognize that only 'monitor interface' provides live, continuously updated data.
Trap categories for this question
Command / output trap
This shows a snapshot, not dynamic updates.
Detailed technical explanation
The 'monitor interface' command leverages the Junos kernel's packet sampling mechanism to poll interface counters every second, displaying delta values (changes since the last update) rather than cumulative totals. This is particularly useful for identifying transient issues like microbursts or intermittent packet loss, where static commands might miss short-lived anomalies. The output includes fields such as input/output packets, errors, and drops, updated in place on the terminal.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
User Interfaces — This question tests User Interfaces — Read the scenario before looking for a memorised answer..
The correct answer is: monitor interface — The 'monitor interface' command in Junos provides real-time, continuously updated packet statistics for a specified interface, making it the correct choice for live troubleshooting. Unlike static commands, it refreshes statistics every second until interrupted, allowing the administrator to observe traffic patterns as they occur.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This JNCIA-JUNOS practice question is part of Courseiva's free Juniper Networks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the JNCIA-JUNOS exam.
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