Junos Commit Options: Check, Synchronize, Confirmed
Which THREE statements about the 'commit' command are correct?
Quick Answer
The correct answer is that the 'commit confirmed 5' command will roll back the configuration after 5 minutes if not confirmed. This is because the Junos commit confirmed option activates a candidate configuration for a specified number of minutes, but if the administrator does not issue a standard 'commit' command within that window, the system automatically reverts to the previous active configuration, preventing lockout from a faulty change. On the JNCIA-Junos exam, this concept tests your understanding of safe configuration practices, often appearing alongside the 'commit check' command—which validates syntax without applying changes—and the 'synchronize' option used on dual Routing Engine systems. A common trap is confusing 'commit confirmed' with a permanent commit; remember that the timer is a safety net, not a delay. For a quick memory tip: think of "confirmed" as a "countdown to rollback"—if you don't confirm before the clock runs out, the change disappears.
⚠ Common exam trap
Candidates often confuse 'commit full' with a validation-skipping command, when in fact it performs a more thorough validation, and they may incorrectly assume that multiple users cannot commit simultaneously in Junos, unlike some other network operating systems.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The 'commit check' command validates the syntax of the candidate configuration.
Option A is correct because 'commit check' parses and validates the candidate configuration's syntax and semantics without actually activating it, so errors are reported before a real commit. Option B is correct because on a dual-RE (redundant Routing Engine) system, 'commit synchronize' commits the candidate configuration on both Routing Engines, keeping the primary and backup REs in sync. Option E is correct because 'commit confirmed 5' activates the configuration but automatically rolls back to the previous configuration after 5 minutes unless the administrator confirms it with a subsequent 'commit'. Option C is wrong because 'commit full' forces a full commit that re-evaluates the entire configuration and does perform validation, rather than skipping it. Option D is wrong because multiple users can be in configuration mode simultaneously; the 'commit' command is not restricted to a single user, though a commit lock may be used to prevent conflicting changes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The 'commit check' command validates the syntax of the candidate configuration.
Why this is correct
'commit check' parses and validates the candidate configuration against the schema without loading it into the running configuration, reporting syntax or semantic errors. This satisfies the stem's requirement for a statement about commit command behaviour on Junos devices.
- ✓
The 'commit synchronize' command is used on a dual-RE system to commit on both REs.
Why this is correct
On dual Routing Engine systems, 'commit synchronize' commits the candidate configuration on both the master and backup REs simultaneously, keeping them consistent. This satisfies the stem's requirement by correctly describing synchronised commit behaviour across redundant control planes.
- ✗
The 'commit full' command activates the configuration without performing any validation.
Why it's wrong here
'commit full' still validates the candidate configuration, then loads and commits it; validation is not skipped. It is tempting because 'full' suggests a forced, unchecked commit, and it would be the right choice when you need to commit all pending changes across every configuration hierarchy at once.
- ✗
The 'commit' command can only be issued when no other users are in configuration mode.
Why it's wrong here
Junos permits multiple users to hold configuration mode simultaneously, and commit operates on the shared candidate configuration regardless of other sessions. It is tempting because exclusive configuration locking exists, and would be correct only when the 'configure exclusive' command has been issued by another user.
- ✓
The 'commit confirmed 5' command will roll back the configuration after 5 minutes if not confirmed.
Why this is correct
'commit confirmed 5' activates the candidate configuration but automatically rolls it back after five minutes unless the administrator issues a confirming commit. This satisfies the stem by correctly describing the safety mechanism that prevents locking out remote management access.
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Same concept, more angles
4 more ways this is tested on JN0-106
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 THREE statements about the commit operation are correct? (Choose three.)
medium- ✓ A.The 'commit check' command validates the syntax of the candidate configuration without activating it.
- ✓ B.After a successful commit, the candidate configuration becomes the active configuration.
- ✓ C.A commit can be scheduled to revert automatically if not confirmed within a certain time.
- D.The candidate configuration is stored in a file named 'juniper.conf' on the flash drive.
- E.A commit operation automatically saves the rescue configuration.
Why A: Option A is correct because 'commit check' performs a syntax and semantic validation of the candidate configuration and reports errors without activating or applying it, leaving the active configuration unchanged. Option B is correct because a successful commit copies the candidate configuration into the active configuration (the running configuration that the device uses), making the candidate the active one. Option C is correct because a commit can be issued with a confirmation timeout (for example, 'commit confirmed 10'), which automatically reverts to the previous configuration unless the commit is confirmed within that period. Option D is not correct because the active configuration is stored in 'juniper.conf' (with backups like juniper.conf.1.gz), while the candidate configuration is held in a separate candidate database, not in 'juniper.conf'. Option E is not correct because the rescue configuration is not saved automatically by a commit; it must be saved explicitly with 'request system configuration rescue save'.
Variation 2. Which TWO statements about the 'commit' operation in Junos are correct?
medium- ✓ A.The commit operation validates syntax before applying, and if errors are found, the commit fails.
- B.The commit operation automatically rolls back changes after 10 minutes if not confirmed.
- C.The commit operation allows you to commit only a specific portion of the configuration.
- D.The commit operation applies the configuration changes at the next system reboot.
- ✓ E.The commit operation activates the candidate configuration as the new active configuration.
Why A: Option A is correct because when you run commit, Junos first performs a syntax check on the candidate configuration, and if any syntax errors are detected, the commit fails and the candidate configuration is not activated. Option E is correct because the commit operation merges the candidate configuration into the active configuration, making it the new running (active) configuration on the device. Option B is incorrect because automatic rollback after 10 minutes only occurs with the 'commit confirmed' command, not a standard commit. Option C is incorrect because Junos commits the entire candidate configuration; partial commits are not supported (you would use configuration groups or 'commit check' for validation instead). Option D is incorrect because commit applies changes immediately, not at the next system reboot.
Variation 3. Which TWO statements are true about the 'commit' operation in Junos?
medium- ✓ A.The commit command validates the configuration syntax before applying it.
- B.The commit command automatically saves the configuration to a file on the hard disk.
- C.After a commit, the candidate configuration is replaced with the active configuration.
- ✓ D.A commit can include a comment for documentation purposes.
- E.A successful commit overwrites the rollback configurations.
Why A: Option A is correct because when you issue commit in Junos, the candidate configuration is first checked for syntax and semantic errors, and only a valid configuration is merged into the active configuration. Option D is correct because Junos supports commit comment "text", which stores a descriptive comment with the committed configuration for documentation and audit purposes. Option B is not correct because commit applies the candidate configuration to the active configuration; it does not by itself save a configuration file to disk, which is done with save or file-related commands. Option C is not correct because after a commit the candidate configuration remains as the working copy and is not replaced by the active configuration. Option E is not correct because a successful commit does not overwrite the rollback configurations; Junos maintains up to 50 previous committed configurations for rollback.
Variation 4. Which THREE statements about commit options are true?
hard- A.'commit full' reinitializes the system.
- ✓ B.'commit confirmed' requires a second commit within the timeout to keep the changes.
- ✓ C.'commit synchronize' commits on both Routing Engines in a chassis cluster.
- ✓ D.'commit check' validates syntax without committing.
- E.'commit and-quit' commits and exits configuration mode.
Why B: Option B is correct because 'commit confirmed' applies the candidate configuration but automatically rolls back to the previous configuration unless a second commit is issued within the confirmation timeout (default 10 minutes), which is useful for preventing lockout. Option C is correct because 'commit synchronize' pushes and commits the configuration on both Routing Engines in a chassis cluster, keeping the primary and backup REs in sync. Option D is correct because 'commit check' performs a syntax and semantic validation of the candidate configuration without activating or committing it, allowing errors to be caught before a real commit. Option A is not correct because 'commit full' does not reinitialize the system; it forces a full commit that re-evaluates the entire configuration rather than only changed portions. Option E is not correct because 'commit and-quit' is not a valid Junos commit option; the correct behavior of committing and leaving configuration mode is achieved with 'commit' followed by 'exit', or 'commit and-quit' is not a recognized command in this context.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This JN0-106 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 JN0-106 exam.