JNCIA-JUNOS Junos Configuration Basics Practice Question
This JNCIA-JUNOS practice question tests your understanding of junos configuration basics. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A Juniper router experiences a power outage. After power is restored, the router fails to boot completely and stops at the loader (U-Boot) prompt. You have console access. Before the outage, you had saved a rescue configuration. How can you load the rescue configuration to recover the system?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Type 'boot rescue' at the loader prompt.
Option B is correct because at the U-Boot loader prompt, the 'boot rescue' command instructs the router to boot using the rescue configuration stored in the /config directory. The rescue configuration is a known-good configuration that can be saved via 'request system configuration rescue save' and is loaded directly by the boot loader when the normal boot process fails.
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.
✗
Type 'load rescue' at the loader prompt.
Why it's wrong here
'load rescue' is a CLI command, not valid at the loader prompt.
✓
Type 'boot rescue' at the loader prompt.
Why this is correct
This boots the device with the rescue configuration.
Related concept
Read the scenario before looking for a memorised answer.
✗
Power cycle with a pin in the reset hole.
Why it's wrong here
This resets the device to factory defaults, not rescue.
✗
Type 'boot -s' to enter single-user mode, then load rescue.
Why it's wrong here
Single-user mode is for password recovery, not for loading rescue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the CLI command 'load rescue' (used in operational mode to merge or replace the candidate configuration) with the boot loader command 'boot rescue', and they assume the loader supports Junos CLI syntax.
Trap categories for this question
Command / output trap
'load rescue' is a CLI command, not valid at the loader prompt.
Detailed technical explanation
How to think about this question
The rescue configuration is stored as a file named 'rescue.conf.gz' in the /config directory on the router's flash. When you issue 'boot rescue' at the U-Boot prompt, the boot loader reads this file and passes it to the Junos kernel during the boot process, effectively overriding the normal configuration. This mechanism is critical for disaster recovery because it allows the router to boot with a minimal, known-working configuration even if the primary configuration is corrupted or missing.
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 Configuration Basics — This question tests Junos Configuration Basics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Type 'boot rescue' at the loader prompt. — Option B is correct because at the U-Boot loader prompt, the 'boot rescue' command instructs the router to boot using the rescue configuration stored in the /config directory. The rescue configuration is a known-good configuration that can be saved via 'request system configuration rescue save' and is loaded directly by the boot loader when the normal boot process fails.
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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Question Discussion
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