Junos File System: Understanding /config and /var/tmp
Which TWO statements are true about the Junos file system? (Choose two.)
Quick Answer
The correct answer includes the statement that /var/tmp is used for temporary storage, as this directory holds transient files like logs, crash data, and core dumps that are cleared upon reboot. This is a fundamental distinction on the Junos file system because /config stores the active and backup configuration files—juniper.conf and juniper.conf.gz—which are critical for device boot and operation, while /var/tmp is explicitly non-persistent. On the JNCIA-Junos exam, this question tests your ability to differentiate between persistent and volatile directories, often appearing as a “choose two” trap where candidates confuse /var/tmp with /config or /var/log. A common memory tip is to think of “tmp” as “temporary” and “config” as “committed”—if it survives a reboot, it belongs in /config; if it vanishes, it belongs in /var/tmp.
⚠ Common exam trap
It's easy for candidates to confuse the /altroot directory with a backup root filesystem, when in fact it is used for alternate root images during software upgrades, not a persistent backup.
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 /config directory contains configuration files.
The /config directory in the Junos file system stores the active and backup configuration files, including juniper.conf and juniper.conf.gz. These files are critical for device operation and are loaded during the boot process.
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 /config directory contains configuration files.
Why this is correct
/config stores the active and candidate configuration files.
- ✓
The /var/tmp directory is used for temporary storage.
Why this is correct
The `/var/tmp` directory on Junos devices is indeed designated for temporary storage. This is a standard convention within UNIX-like operating systems, including Junos OS, where applications and processes write transient data. Files placed here are typically non-persistent across reboots or are periodically cleared, making it a suitable location for temporary operational files. This accurately describes a fundamental aspect of the Junos file system's structure and purpose.
- ✗
The /altroot directory is a backup root filesystem.
Why it's wrong here
There is no standard /altroot directory; backup root is /altroot on some systems but not common Junos.
- ✗
The /kernel directory contains the operating system kernel.
Why it's wrong here
The kernel is loaded from /boot, not a /kernel directory.
- ✗
The root directory (/) is a RAM disk.
Why it's wrong here
The root filesystem is stored on flash, not a RAM disk.
Go deeper
Related to this question
About these practice questions
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Same concept, more angles
1 more way 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 Junos OS file system are true? (Choose three.)
hard- A.The /etc directory contains all log files
- B.The /altroot directory is used for user-uploaded files
- ✓ C.The active configuration is stored in the /config directory
- ✓ D.Log files are typically stored in /var/log
- ✓ E.The file system is UNIX-like with directories such as /, /var, /config
Why C: 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`.
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.