JN0-106 User Interfaces Practice Question
After upgrading Junos, a router fails to boot with a file system error. The admin needs to recover the system from the backup partition. Which key should be pressed during boot to access the boot menu?
⚠ Common exam trap
The trap here is that candidates familiar with Cisco IOS might confuse the Juniper boot menu access (Space bar) with Cisco's Ctrl+Break or other interrupt keys, leading them to select Ctrl+C or Esc incorrectly.
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
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Space
Pressing the Space bar during the boot process on a Juniper device interrupts the normal boot sequence and presents the boot menu. From this menu, the administrator can select the backup Junos partition (typically labeled as '1' or 'backup') to recover the system when the primary partition has a file system error.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Ctrl+C
Why it's wrong here
Pressing Ctrl+C during the Junos boot sequence may interrupt the current boot attempt or halt autoboot, but it does not trigger the boot loader menu used for selecting an alternate root partition. On Junos devices, Ctrl+C is not a recognized shortcut for invoking the boot menu; it can leave the system at a prompt or cancel a disk scan, but it will not let you choose a different Junos snapshot or partition.
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Esc
Why it's wrong here
The Esc key is not used in the Junos boot loader to open the partition selection menu. In many boot environments, Esc might cancel a delay timer or dismiss a splash screen, but on Junos the boot menu is intentionally invoked only by the Space key. Pressing Esc may briefly stop the countdown or clear a message, but the router will then continue with the default boot partition, which is not helpful when trying to recover from a failed filesystem.
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Enter
Why it's wrong here
Pressing Enter at the Junos boot prompt accepts the default action, which is to boot the primary Junos partition. The 'Hit [Enter] to immediately boot' message explicitly indicates that Enter will bypass the boot menu and start the current default image immediately. This is the opposite of what you want when the router fails to boot due to a corrupt filesystem, because it does not allow you to select a backup or alternate partition.
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Space
Why this is correct
Pressing the Space bar at the Junos boot prompt halts the automatic boot and displays the boot loader menu, which lists available Junos partitions and snapshots. This menu lets you select an alternate root partition, such as a prior stable snapshot or the other disk, which is essential when the current primary partition has a corrupted filesystem and cannot boot. The message 'Hit [Space] to halt, [Enter] to immediately boot' specifically identifies Space as the correct key to reach this recovery and partition-selection interface.
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About these practice questions
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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.