JNCIA-JUNOS Junos OS Fundamentals Practice Question
This JNCIA-JUNOS practice question tests your understanding of junos os fundamentals. 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.
Which THREE statements about the Junos OS file system are true? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The active configuration is stored in the /config directory
Option C is correct because the active configuration in Junos OS is stored as a file named `junos.conf` in the `/config` directory. This file is used by the system to load the running configuration at boot time, and it is distinct from the candidate configuration stored in `/var/db/config`.
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.
✗
The /etc directory contains all log files
Why it's wrong here
/etc contains configuration files for system services, not logs.
✗
The /altroot directory is used for user-uploaded files
Why it's wrong here
/altroot is a backup root partition, not for user storage.
✓
The active configuration is stored in the /config directory
Why this is correct
The file juniper.conf.gz is in /config.
Related concept
Read the scenario before looking for a memorised answer.
✓
Log files are typically stored in /var/log
Why this is correct
Messaging, audit, and other logs are in /var/log.
Related concept
Read the scenario before looking for a memorised answer.
✓
The file system is UNIX-like with directories such as /, /var, /config
Why this is correct
Junos is based on FreeBSD, so it has a UNIX file system structure.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the `/etc` directory (which stores system configs, not logs) with the standard Linux convention, or they mistakenly think `/altroot` is for user files instead of its actual purpose as a backup root filesystem.
Detailed technical explanation
How to think about this question
Junos OS uses a UNIX-like file system hierarchy, where `/` is the root, `/var` holds variable data like logs and databases, and `/config` stores the active configuration. The `/altroot` directory is a separate partition that can be used as an alternate root during system upgrades or recovery, ensuring the system can boot even if the primary root is corrupted. Understanding this layout is critical for tasks like log retrieval (`show log`) and configuration management (`commit`).
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.
Junos OS Fundamentals — This question tests Junos OS Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The active configuration is stored in the /config directory — Option C is correct because the active configuration in Junos OS is stored as a file named `junos.conf` in the `/config` directory. This file is used by the system to load the running configuration at boot time, and it is distinct from the candidate configuration stored in `/var/db/config`.
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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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.
Question Discussion
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