JN0-106 User Interfaces Practice Question
A junior engineer is troubleshooting a routing issue and wants to see the route table for IPv4 unicast routes. Which command will display this information?
⚠ Common exam trap
Many candidates confuse the routing table (RIB) with the forwarding table (FIB), or they may think 'show route protocol bgp' shows all routes, when it only shows routes from a specific protocol.
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
✓
show route table inet.0
The command 'show route table inet.0' displays the IPv4 unicast route table in Junos. The inet.0 table is the default routing table for IPv4 unicast routes, containing all active routes learned via various protocols (e.g., OSPF, BGP, static). This command is the standard way to view the IPv4 unicast routing information base (RIB) on Juniper devices.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
show route table inet.0
Why this is correct
The `show route table inet.0` command is the correct choice because `inet.0` is the default IPv4 unicast routing table on Junos. When a junior engineer needs to investigate a generic routing issue involving IPv4 destinations, this command displays the active routes, protocol next-hops, and preference/metric values that determine how packets are forwarded. It directly exposes whether the expected route is present, hidden, or missing, which is the first step in diagnosing reachability problems. Unlike protocol-specific or forwarding-table views, this master table includes all protocols that contribute to IPv4 forwarding decisions.
- ✗
show route table inet6.0
Why it's wrong here
The `show route table inet6.0` command is incorrect for this scenario because it displays only the IPv6 unicast routing table. If the routing issue involves IPv4 destinations, which is almost always implied by a generic 'routing issue' unless IPv6 is explicitly mentioned, filtering to `inet6.0` would omit the very routes the engineer needs to inspect. This command is useful only when troubleshooting IPv6 connectivity, such as missing RA-learned routes or BGP IPv6 prefixes, but it would not show IPv4 entries like `10.0.0.0/8` or `192.168.1.0/24`. Running it for an IPv4 problem would produce an empty or irrelevant table, leading the engineer to mistakenly conclude that routing is down when the issue is actually in the IPv4 table.
- ✗
show route forwarding-table
Why it's wrong here
The `show route forwarding-table` command is incorrect because it displays the forwarding table (also known as the FIB or PFE forwarding table), not the route table (RIB). The forwarding table is derived from the route table and contains only the active next-hops that are programmed into the Packet Forwarding Engine, with no protocol preference or route origin information. It is used to verify what is actually being forwarded in hardware or software, but it does not show all candidate routes, hidden routes, or secondary paths that the routing table holds. For troubleshooting why a route is not being selected or why a specific path is preferred, the engineer must examine the route table (`inet.0`), because it shows the routing decision process before the FIB is populated.
- ✗
show route protocol bgp
Why it's wrong here
The `show route protocol bgp` command is incorrect because it filters the route table to display only routes learned or advertised by the BGP protocol. A generic routing issue could be caused by an OSPF, IS-IS, static, or directly connected route problem, and this command would hide those entries entirely. Even if the root cause involves BGP, this command shows only BGP-route entries and does not reveal the full routing table context, such as how a BGP route competes with a static or IGP route for the same prefix. To troubleshoot comprehensively, the engineer should view the complete IPv4 routing table in `inet.0` and apply protocol filters only after narrowing down the suspected source, not at the outset.
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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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.