Junos OS Upgrade with Graceful Switchover (GRES)
Which three steps are part of a typical software upgrade process on a Juniper device? (Choose three.)
⚠ Common exam trap
The trap here is that candidates may mistakenly think interfaces must be shut down before an upgrade (option C), confusing Junos' non-disruptive upgrade process with Cisco IOS procedures where manual interface shutdown is often recommended to prevent routing flaps during the reload.
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
✓
Issue the request system software add command
Option A is correct because the request system software add command is the standard Junos CLI command used to install a new software image onto the device, validating and unpacking it into the alternate partition. Option B is correct because the software image must first be downloaded to the device, and /var/tmp is the conventional directory used for staging the Junos package before installation. Option E is correct because after the new image is added, the device must be rebooted so it boots from the newly installed software on the alternate partition. Option C is not part of the process because interfaces do not need to be manually shut down; the reboot handles the transition. Option D is not required because Junos installs the new image to the alternate partition and the old image can remain, so deleting it beforehand is unnecessary and not a standard step.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Issue the request system software add command
Why this is correct
The `request system software add` command is the central Junos CLI operation that ingests the software package, typically specified as a local file path or an HTTP/FTP URL. It performs integrity and version checks, then unpacks the image onto the alternate boot partition so it becomes the next active image on the next reboot. It can also include the `reboot` option to automate the restart sequence, but the command itself is what officially 'adds' the package.
- ✓
Download the image to /var/tmp
Why this is correct
Downloading the image to `/var/tmp` is the standard preparatory step because this directory is a persistent staging area that remains available across a reboot, whereas `/tmp` may be cleared. Junos software packages are often large (hundreds of MB), and `/var/tmp` has sufficient space and is specifically referenced in Juniper's documentation as the recommended location. After staging, you can either run `request system software add /var/tmp/<image>` or use a URL if you prefer not to store it locally, but local staging simplifies troubleshooting and installation.
- ✗
Shut down all interfaces
Why it's wrong here
Manual interface shutdown is not part of the Junos software upgrade procedure because the system automatically manages interface state during the reboot; the data plane is taken down and reinitialized by the kernel. Preemptively shutting down interfaces introduces unnecessary administrative overhead and risks connectivity to the management plane, which could complicate the upgrade. The only outage is the brief reboot period, regardless of whether interfaces are administratively down, so no extra step is needed.
- ✗
Delete the old image before adding the new one
Why it's wrong here
Unlike many other network OSes, Junos keeps the previous software image on separate storage (often the other boot partition) to enable rollback if the new image fails to boot or has operational issues. Deleting the old image before adding the new one would destroy the rollback capability and is counterproductive, as the storage footprint of a few images is generally negligible. The recommended practice is to add the new image while preserving the existing one, then clean up only after the new image has been verified and the rollback window has closed.
- ✓
Reboot the device
Why this is correct
A reboot is the final step that actually makes the device boot from the newly added software image, switching the active and inactive partitions. Without this restart, the device continues to run the current version, and the staged image remains dormant, so the upgrade would be incomplete. The `request system software add` command can be issued with the `reboot` option to perform the reboot automatically after a successful installation and validation, or you can issue a separate `request system reboot` command if you need to schedule the outage.
Go deeper
Related to this question
About these practice questions
Courseiva writes every JN0-106 question from scratch — 326 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.