The answer is that the interface is up and the physical link is up, indicating a fully operational connection. This is correct because "Admin up" means the interface has been administratively enabled in the Junos configuration—no shutdown command has been applied—while "Link up" confirms that the physical layer has detected a valid carrier signal from the connected device. On the JNCIA-Junos exam, this concept tests your understanding of interface states and the distinction between administrative control and physical-layer status; a common trap is confusing "Admin up" with "Link up" or assuming one implies the other. Remember that both conditions must be true for traffic to flow, and a "Link down" state despite "Admin up" often points to a cable or peer issue. A useful memory tip is to think of "Admin" as the software switch and "Link" as the hardware handshake—both must be flipped on for the interface to work.
JNCIA-JUNOS User Interfaces Practice Question
This JNCIA-JUNOS practice question tests your understanding of user interfaces. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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
show interfaces terse ge-0/0/0
Interface Admin Link Proto Local Remote
ge-0/0/0 up up inet 192.168.1.1/24
inet6 fe80::1/64
Refer to the exhibit. An engineer sees that the interface ge-0/0/0 has 'Admin up' and 'Link up'. What does this indicate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The interface is up and the physical link is up.
When an interface shows 'Admin up' and 'Link up', it means the interface has been administratively enabled (no 'shutdown' command applied) and the physical layer has detected a carrier signal from the connected device. In Junos, this is the normal operational state for a functioning interface, confirming that both the administrative configuration and the physical link are active.
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 interface is administratively down.
Why it's wrong here
Admin is up, so it is not administratively down.
✗
The interface is a loopback interface.
Why it's wrong here
The name ge-0/0/0 indicates a Gigabit Ethernet interface, not loopback.
✗
The interface has an IPv6 address only.
Why it's wrong here
It has both IPv4 and IPv6 addresses.
✓
The interface is up and the physical link is up.
Why this is correct
Admin up means enabled; Link up means physical connection is active.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse 'Admin up' with 'Link up', thinking one implies the other, or incorrectly assume 'Admin up' alone means the interface is fully operational, when in fact both must be 'up' for traffic to flow.
Detailed technical explanation
How to think about this question
In Junos, the 'show interfaces terse' command displays administrative and operational statuses; 'Admin up' means the interface has not been disabled via 'set interfaces ge-0/0/0 disable', and 'Link up' indicates the physical layer (e.g., Ethernet autonegotiation) has successfully established a link. This state is required for Layer 2 and Layer 3 protocols to function, and it is verified by the 'show interfaces ge-0/0/0' command which also displays counters and errors.
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 interface is up and the physical link is up. — When an interface shows 'Admin up' and 'Link up', it means the interface has been administratively enabled (no 'shutdown' command applied) and the physical layer has detected a carrier signal from the connected device. In Junos, this is the normal operational state for a functioning interface, confirming that both the administrative configuration and the physical link are active.
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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