JN0-106 Operational Monitoring and Maintenance Practice Question
Which two commands can be used to display real-time interface information? (Choose two.)
⚠ Common exam trap
Candidates often confuse static `show` commands (like `show interfaces`) with real-time `monitor` commands, or assuming that any command displaying data is real-time, when only `monitor` commands provide live, updating output.
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
✓
monitor interface
Option A, `monitor interface`, is correct because it provides a real-time, continuously updating view of interface statistics such as traffic counters, errors, and link state on Juniper devices. Option B, `monitor traffic`, is correct because it captures and displays live packet-level traffic on an interface, showing real-time data as packets traverse the interface. Option C, `show log`, is incorrect because it displays stored log file contents rather than live interface information. Option D, `request system reboot`, is incorrect because it reboots the device and does not display interface data. Option E, `show system storage`, is incorrect because it reports disk and filesystem usage, not real-time interface information.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
monitor interface
Why this is correct
monitor interface is a Junos operational command that provides continuously updated, real-time statistics for a specified interface, including current input/output rates, packet counts, and error counters. It refreshes at a fixed interval, allowing you to observe dynamic changes in interface utilization and detect transient issues like CRC errors or drops that a one-time show command might miss. This makes it the first choice for live health checks of physical or logical interfaces.
- ✓
monitor traffic
Why this is correct
monitor traffic is an operational command that captures and displays the actual packets transiting an interface in real time, using the same underlying logic as tcpdump on Junos. It shows frame headers and packet summaries, enabling you to inspect protocol handshakes or unexpected broadcast storms at the packet level. Unlike monitor interface, it focuses on granular packet content rather than aggregated counter statistics.
- ✗
show log
Why it's wrong here
show log displays messages that have already been written to the system's log files, such as interface transitions, login successes, or routing protocol events. It is a historical snapshot of past activity, not a live feed; to follow a log in real time, you would use monitor start or monitor traffic for interface data. Therefore, it cannot satisfy the requirement for real-time interface display.
- ✗
request system reboot
Why it's wrong here
request system reboot is a system control command that shuts down and restarts the Junos device, causing all interfaces to go down and then recover during the reboot process. It does not display any interface information; its purpose is to perform a disruptive maintenance action, not to provide real-time monitoring. Consequently, it is completely unrelated to the operational need described in the question.
- ✗
show system storage
Why it's wrong here
show system storage reports on disk space utilization, file system mount points, and available flash capacity, which are critical for system health but independent of interface operation. It provides no data about interface status, traffic rates, or packet flow, and the output is a static point-in-time measurement rather than a real-time stream. Thus, it does not fulfill the command requirement for displaying real-time interface information.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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JA
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.