Quick Answer
The answer is the `show route forwarding-table destination 10.0.0.1` command. This is correct because even when a route appears in the routing table (RIB), it may not have been successfully programmed into the forwarding table (FIB) due to a hardware or kernel programming failure, causing intermittent traffic drops. The command directly verifies the actual forwarding entry used by the router to forward packets, isolating whether the mismatch lies between the RIB and FIB. On the JNCIA-Junos exam, this scenario tests your understanding that the routing table is a control-plane construct, while the forwarding table is the data-plane reality; a common trap is assuming a route in the RIB guarantees traffic delivery. Remember the key distinction: RIB shows what the router knows, FIB shows what the router does. A helpful memory tip is “RIB to think, FIB to ship”—always verify the forwarding table when traffic drops despite a valid route.
This JNCIA-JUNOS practice question tests your understanding of operational monitoring and maintenance. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A network engineer notices that traffic to a critical server is being dropped intermittently. The server is reachable via a static route on the Juniper router. The engineer checks the routing table and sees the route is present. Which operational command should the engineer use next to isolate the issue?
show interfaces terse
Why wrong: Shows interface status, not forwarding details.
show route 10.0.0.1
Why wrong: Shows the routing table, but the route is already present.
show arp
Why wrong: Shows ARP entries, not relevant for forwarding drops.
show route forwarding-table destination 10.0.0.1
Shows the forwarding table entry used by the PFE.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
show route forwarding-table destination 10.0.0.1
Option D is correct because the `show route forwarding-table destination 10.0.0.1` command displays the actual forwarding entry in the kernel's forwarding table (FIB). Even if the route is present in the routing table (RIB), a mismatch between the RIB and FIB can cause traffic drops. This command directly verifies whether the route has been installed into the forwarding table, isolating the issue to a possible hardware or kernel programming failure.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
show interfaces terse
Why it's wrong here
Shows interface status, not forwarding details.
show route 10.0.0.1
Why it's wrong here
Shows the routing table, but the route is already present.
show arp
Why it's wrong here
Shows ARP entries, not relevant for forwarding drops.
show route forwarding-table destination 10.0.0.1
Why this is correct
Shows the forwarding table entry used by the PFE.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates assume a route present in the routing table guarantees it is being used for forwarding, but Junos separates control plane (RIB) from forwarding plane (FIB), so the FIB must be checked separately to identify programming failures.
Trap categories for this question
Command / output trap
Shows interface status, not forwarding details.
Detailed technical explanation
In Junos, the routing table (RIB) and forwarding table (FIB) are separate; the RIB is managed by the routing protocol process (rpd), while the FIB is programmed into the kernel and Packet Forwarding Engine (PFE). A route present in the RIB but missing from the FIB can occur due to memory pressure, route resolution failures, or a stale next-hop. The `show route forwarding-table destination` command queries the kernel's FIB directly, allowing the engineer to confirm if the route is actually being used for packet forwarding.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Operational Monitoring and Maintenance — This question tests Operational Monitoring and Maintenance — Read the scenario before looking for a memorised answer..
The correct answer is: show route forwarding-table destination 10.0.0.1 — Option D is correct because the `show route forwarding-table destination 10.0.0.1` command displays the actual forwarding entry in the kernel's forwarding table (FIB). Even if the route is present in the routing table (RIB), a mismatch between the RIB and FIB can cause traffic drops. This command directly verifies whether the route has been installed into the forwarding table, isolating the issue to a possible hardware or kernel programming failure.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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