The answer is the 'show interfaces extensive | save' command and the 'show interfaces statistics | save' command. These are correct because the 'save' pipe modifier captures the current output of a Junos operational command and writes it directly to a file, creating a static snapshot of interface counters such as packets, errors, and discards at that precise moment. On the JNCIA-Junos exam, this tests your understanding of Junos CLI operational mode and the difference between real-time monitoring commands like 'monitor interface' and point-in-time capture using 'save'. A common trap is confusing 'save' with 'monitor' or 'set'—remember that 'save' writes a static file, while 'monitor' streams live updates. To capture interface statistics to file for later analysis, always pipe the show command output to 'save' followed by a file path. A helpful memory tip: "Save a snapshot, monitor the movie."
JNCIA-JUNOS Operational Monitoring and Maintenance Practice Question
This JNCIA-JUNOS practice question tests your understanding of operational monitoring and maintenance. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
Which two commands can be used to capture the current interface statistics and save them for later analysis? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
show interfaces statistics | save /var/log/iface_stats.txt
Option C is correct because the 'show interfaces statistics' command displays current interface counters (e.g., input/output packets, errors, discards) and piping the output to '| save /var/log/iface_stats.txt' writes the snapshot to a file for later analysis. This allows you to capture a point-in-time record of interface statistics without ongoing monitoring.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
file archive interface-statistics
Why it's wrong here
Not a valid command.
✗
request system statistics interface
Why it's wrong here
Not a valid command.
✓
show interfaces statistics | save /var/log/iface_stats.txt
Why this is correct
Saves interface statistics output to a file.
Related concept
Read the scenario before looking for a memorised answer.
✓
show interfaces extensive | save /var/log/iface_extensive.txt
Why this is correct
Saves extensive interface output to a file.
Related concept
Read the scenario before looking for a memorised answer.
✗
monitor interface traffic | save /var/log/iface_traffic.txt
Why it's wrong here
Monitor command does not support the 'save' option.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse 'monitor interface traffic' (a real-time, continuous command) with 'show interfaces statistics' (a static snapshot), or assume that 'request system statistics interface' is a valid Junos command when it is not, leading them to select option B or E incorrectly.
Trap categories for this question
Command / output trap
Not a valid command.
Detailed technical explanation
How to think about this question
The 'show interfaces statistics' command retrieves counters from the Packet Forwarding Engine (PFE) and Routing Engine (RE) for each interface, including unicast packets, multicast packets, and error counters. The '| save' operation writes the exact output to a file, which can be compared later with another snapshot to compute delta values for traffic growth or error accumulation. In real-world scenarios, this is used for capacity planning or troubleshooting intermittent issues by comparing historical snapshots.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the JNCIA-JUNOS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Operational Monitoring and Maintenance — This question tests Operational Monitoring and Maintenance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: show interfaces statistics | save /var/log/iface_stats.txt — Option C is correct because the 'show interfaces statistics' command displays current interface counters (e.g., input/output packets, errors, discards) and piping the output to '| save /var/log/iface_stats.txt' writes the snapshot to a file for later analysis. This allows you to capture a point-in-time record of interface statistics without ongoing monitoring.
What should I do if I get this JNCIA-JUNOS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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