Quick Answer
The answer is the commit confirmed command. This is the correct choice because it applies configuration changes with a default 10-minute rollback timer; if the engineer does not explicitly confirm the commit within that window, Junos automatically reverts to the previous configuration, ensuring that any disruption to active sessions is temporary and not permanent. On the JNCIA-Junos exam, this concept tests your understanding of safe configuration practices during maintenance windows, often appearing in scenario-based questions where a trap answer is the standard commit command—which applies changes immediately with no safety net. A common memory tip is to think of commit confirmed as a “safety net” that gives you a ten-minute test drive; if the network breaks, Junos catches you by rolling back automatically. Remember the mnemonic “C-C for Confirmed Commit” to link the command with its rollback safety feature.
This JNCIA-JUNOS practice question tests your understanding of user interfaces. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
During a maintenance window, a network engineer is about to commit changes but wants to ensure no active sessions are disrupted. Which command should they run first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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.
commit confirmed
Commits with a timeout; if session is lost, automatically rolls back.
commit check
Why wrong: Only validates syntax, does not prevent session disruption.
commit synchronize
Why wrong: Used for multi-chassis synchronization, not for session safety.
commit at
Why wrong: Schedules a commit, but does not provide automatic rollback on session loss.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
commit confirmed
Option A is correct because the 'commit confirmed' command allows the engineer to apply changes with a default 10-minute rollback timer. If the commit is not confirmed within that window, Junos automatically reverts to the previous configuration, ensuring that any disruption caused by the changes is temporary and active sessions are not permanently affected.
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.
commit confirmed
Why this is correct
Commits with a timeout; if session is lost, automatically rolls back.
Clue confirmation
The clue words "first", "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
commit check
Why it's wrong here
Only validates syntax, does not prevent session disruption.
commit synchronize
Why it's wrong here
Used for multi-chassis synchronization, not for session safety.
commit at
Why it's wrong here
Schedules a commit, but does not provide automatic rollback on session loss.
Common exam traps
The trap here is that candidates often confuse 'commit check' as a safe way to test changes, but it only validates syntax, not runtime behavior, and provides no automatic rollback to protect active sessions if the changes cause disruption.
Detailed technical explanation
The 'commit confirmed' command leverages Junos's event-based rollback system, which starts a timer (default 10 minutes, configurable with 'commit confirmed <minutes>'). If the engineer does not issue 'commit check' or 'commit' to confirm the changes before the timer expires, the Junos kernel triggers a rollback to the previous active configuration, effectively undoing all changes. This is particularly useful in production networks where a misconfiguration could drop BGP sessions or OSPF adjacencies; the automatic rollback ensures that the network self-heals without manual intervention.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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: commit confirmed — Option A is correct because the 'commit confirmed' command allows the engineer to apply changes with a default 10-minute rollback timer. If the commit is not confirmed within that window, Junos automatically reverts to the previous configuration, ensuring that any disruption caused by the changes is temporary and active sessions are not permanently affected.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "first", "which command". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which TWO statements are true about the 'commit confirmed' command? (Choose two.)
hardWhy B: Option B is correct because the default timeout for the 'commit confirmed' command in Junos is 10 minutes. If no confirmation commit is issued within that period, the system automatically rolls back to the previous configuration, ensuring network stability during remote changes.
Last reviewed: Jun 24, 2026
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