The answer is that the candidate configuration has an IP address change. This is correct because the show | compare command in Junos displays the differences between the candidate and the active committed configuration, and in this output it explicitly shows the address 192.168.1.1/24 being replaced with 192.168.1.2/24 under the [edit interfaces ge-0/0/0 unit 0 family inet] hierarchy. On the JNCIA-Junos exam, this command tests your ability to interpret configuration changes before committing them, often appearing in scenario-based questions where you must identify what modification was made. A common trap is confusing a simple IP address change with a full interface reconfiguration or a rollback; remember that the plus sign (+) indicates the new line and the minus sign (-) indicates the removed line. For a quick memory tip, think of show | compare as a “diff” tool: plus adds, minus removes, so a line with both signs on the same hierarchy means a value replacement, not a deletion.
JNCIA-JUNOS User Interfaces Practice Question
This JNCIA-JUNOS practice question tests your understanding of user interfaces. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
Exhibit
user@router# show | compare rollback 0
[edit interfaces ge-0/0/0 unit 0 family inet]
+ address 192.0.2.1/24;
- address 10.0.0.1/24;
Refer to the exhibit. An engineer runs the command shown. What does this output indicate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The candidate configuration has an IP address change.
The output shows the candidate configuration differs from the committed configuration, as indicated by the 'show | compare' command displaying a change under the [edit interfaces ge-0/0/0 unit 0 family inet] hierarchy. Specifically, it shows the address 192.168.1.1/24 being replaced with 192.168.1.2/24, which is an IP address change. This confirms option B is correct because the candidate configuration has an IP address change that has not yet been committed.
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 candidate configuration matches the committed configuration.
Why it's wrong here
Differences exist, so they do not match.
✓
The candidate configuration has an IP address change.
Why this is correct
The + and - lines indicate a change from 10.0.0.1 to 192.0.2.1.
Related concept
Read the scenario before looking for a memorised answer.
✗
The rollback 0 configuration is being displayed.
Why it's wrong here
The comparison is against rollback 0, but the output shows differences, not the full config.
✗
The interface ge-0/0/0 has been deleted.
Why it's wrong here
Only the address changed, not the interface itself.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'show | compare' with 'show configuration | display set' or assume no output means no candidate changes exist, but in reality, 'show | compare' outputs only differences, and any output indicates a pending change that does not match the committed configuration.
Trap categories for this question
Command / output trap
The comparison is against rollback 0, but the output shows differences, not the full config.
Detailed technical explanation
How to think about this question
The 'show | compare' command in Junos OS uses the candidate configuration (stored in /config/juniper.conf) and compares it to the active committed configuration using a diff algorithm; it outputs only the lines that differ, prefixed with '+' for additions and '-' for removals. Under the hood, Junos maintains a separate candidate database that is only applied to the forwarding plane upon commit, allowing operators to stage changes safely. In real-world scenarios, this command is critical for auditing changes before commit, especially in multi-engineer environments where uncommitted changes could cause service disruptions if not reviewed.
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.
User Interfaces — This question tests User Interfaces — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The candidate configuration has an IP address change. — The output shows the candidate configuration differs from the committed configuration, as indicated by the 'show | compare' command displaying a change under the [edit interfaces ge-0/0/0 unit 0 family inet] hierarchy. Specifically, it shows the address 192.168.1.1/24 being replaced with 192.168.1.2/24, which is an IP address change. This confirms option B is correct because the candidate configuration has an IP address change that has not yet been committed.
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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