The answer is that an active route in Junos must have a valid next hop and is the route selected for installation into the forwarding table. This is correct because the Junos routing table can hold multiple routes to the same destination, but only the best route—determined by protocol preference and metric—becomes active, and it must have a reachable next hop to be placed into the Packet Forwarding Engine’s forwarding information base. On the JNCIA-Junos exam, this concept tests your understanding of route selection and the separation between the routing table and the forwarding table; a common trap is assuming all routes in the routing table are active, when in fact only the winning route with a valid next hop is used for packet forwarding. Remember the mnemonic “Active Needs a Hop” to recall that an active route always requires a valid next hop to be installed in the FIB.
JNCIA-JUNOS Routing Fundamentals Practice Question
This JNCIA-JUNOS practice question tests your understanding of routing fundamentals. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO statements about active routes in the Junos routing table are correct?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
An active route is installed in the forwarding table.
Option C is correct because an active route in Junos is one that is selected as the best route for a given prefix and is installed in the forwarding table (the FIB). The forwarding table is used by the Packet Forwarding Engine (PFE) to make actual forwarding decisions, so only active routes are placed there.
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.
✗
All routes in the routing table are active.
Why it's wrong here
Only the best route for a prefix is active.
✗
Multiple active routes can exist for the same prefix.
Why it's wrong here
Only one active route per prefix (unless ECMP).
✓
An active route is installed in the forwarding table.
Why this is correct
Active routes are used for forwarding.
Related concept
Read the scenario before looking for a memorised answer.
✓
An active route must have a valid next hop.
Why this is correct
Without a valid next hop, the route cannot be active.
Related concept
Read the scenario before looking for a memorised answer.
✗
An active route is always preferred over a passive route.
Why it's wrong here
Passive refers to a route not being active; the term is not standard.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'active route' with 'all routes in the table' or think multiple active routes can coexist for the same prefix, but Junos strictly selects only one active route per prefix based on route preference.
Detailed technical explanation
How to think about this question
In Junos, the routing table (inet.0) holds all routes learned from various protocols (OSPF, BGP, static, etc.), but only the route with the lowest preference value (e.g., 10 for OSPF, 170 for BGP) becomes active and is copied to the forwarding table. The 'show route active-path' command displays only active routes, and the 'route-active' flag in the output indicates this status. A route can be active even if its next hop is unresolved (e.g., a recursive next hop pointing to an unreachable gateway), but it must have a valid next hop to be installed in the forwarding table.
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.
Routing Fundamentals — This question tests Routing Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: An active route is installed in the forwarding table. — Option C is correct because an active route in Junos is one that is selected as the best route for a given prefix and is installed in the forwarding table (the FIB). The forwarding table is used by the Packet Forwarding Engine (PFE) to make actual forwarding decisions, so only active routes are placed there.
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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