JN0-106 User Interfaces Practice Question
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::1/64Refer to the exhibit. An engineer sees that the interface ge-0/0/0 has 'Admin up' and 'Link up'. What does this indicate?
⚠ Common exam trap
Watch out — candidates often 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.
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
✓
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.
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
The exhibit shows 'Admin up' in the interface status output, which means the interface has not been administratively disabled. In Junos, an administratively down interface would display 'Admin down' or 'Administratively Down' and would not forward traffic even if a cable were connected. Because the administrative state is explicitly up, this option contradicts the evidence and is incorrect.
- ✗
The interface is a loopback interface.
Why it's wrong here
The interface name ge-0/0/0 designates a physical Gigabit Ethernet interface located on FPC 0, PIC 0, and port 0, not a loopback. Loopback interfaces in Junos are virtual and named lo0, and they do not have a physical link state. The presence of a physical link status ('Link up') in the exhibit confirms this is a physical interface, so this option is incorrect.
- ✗
The interface has an IPv6 address only.
Why it's wrong here
The exhibit lists both an IPv4 address (such as 192.0.2.1/24) and an IPv6 address (such as 2001:db8::1/64) on the same interface. Junos supports multiple address families on a single interface, so seeing an inet6 address does not exclude IPv4. The statement that the interface has an IPv6 address only is factually wrong based on the address configuration shown.
- ✓
The interface is up and the physical link is up.
Why this is correct
The 'Admin up' state indicates the interface is administratively enabled, while 'Link up' indicates the physical layer has detected a valid link signal from the connected peer. When both are up, the interface is operationally up and able to carry traffic according to the configured protocol families. This accurately matches the exhibit, making it the correct answer.
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
Go deeper
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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.