JN0-106 Networking Fundamentals Practice Question
A medium-sized enterprise has its headquarters (HQ) and a remote branch office connected via a dedicated point-to-point link. The HQ router (Juniper MX) has interface ge-0/0/1 with IP 10.0.0.1/30 connected to the branch router (Juniper SRX) interface ge-0/0/0 with IP 10.0.0.2/30. The branch LAN is 192.168.2.0/24, and the HQ LAN is 10.0.1.0/24. The branch router has a default route pointing to 10.0.0.1. The HQ router has a static route for 192.168.2.0/24 with next-hop 10.0.0.2, but it was recently changed incorrectly to point to 10.0.0.10 due to a configuration error. Users at the branch report that they can access the internet via the HQ router but cannot reach the HQ LAN's file server at 10.0.1.100. From the HQ router, you can ping the branch router's interface IP (10.0.0.2) successfully, but you cannot ping any device in the branch LAN (192.168.2.0/24). You check the routing table on the HQ router and see that the static route for 192.168.2.0/24 points to 10.0.0.10. What is the most appropriate corrective action?
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
✓
Change the static route on the HQ router to point to 10.0.0.2.
The correct action is D: change the static route on the HQ router for 192.168.2.0/24 to point to 10.0.0.2, the actual next-hop IP of the branch router's ge-0/0/0 interface. The HQ router currently has the route pointing to 10.0.0.10, which is not a valid next hop on the 10.0.0.0/30 point-to-point link, so traffic destined for the branch LAN is dropped or unresolved even though 10.0.0.2 is directly reachable. Correcting the next hop restores forwarding to 192.168.2.0/24 and allows return traffic to reach the HQ LAN. Option A is unnecessary because the branch router already has a default route via 10.0.0.1, which covers 10.0.1.0/24. Option B is wrong because removing the HQ static route would not fix the misconfigured next hop and would leave the branch LAN unreachable from HQ. Option C is irrelevant because proxy ARP does not repair an invalid static route next hop.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add a static route on the branch router for 10.0.1.0/24 pointing to 10.0.0.1.
Why it's wrong here
Adding a static route on the branch router for 10.0.1.0/24 pointing to 10.0.0.1 is both redundant and ineffective. The branch router already has a default route to 10.0.0.1, which matches the HQ LAN (10.0.1.0/24) and forwards traffic correctly, so this action changes nothing for traffic from branch to HQ. The actual problem is the HQ router's incorrect next-hop for the branch LAN, and this option does not alter the HQ router's routing table at all, so HQ-to-branch traffic continues to fail.
- ✗
Remove the static route and rely on the default route on the branch router.
Why it's wrong here
Removing the static route from the HQ router would eliminate the only route (even though it is misconfigured) to the branch LAN, causing the HQ router to drop those packets or send them out its default route toward the internet. The branch router's default route only handles traffic from the branch toward HQ, not the reverse direction; routing is destination-based on each router individually. This action makes the problem worse rather than fixing it, so it is incorrect.
- ✗
Enable proxy ARP on the HQ router's ge-0/0/1 interface.
Why it's wrong here
Proxy ARP on the HQ router's ge-0/0/1 interface would only allow the router to answer ARP requests for other IP addresses on that subnet; it cannot create or repair an IP route in the routing table. The issue here is a static route with an invalid next-hop (10.0.0.1), and the router will still discard packets destined for the branch LAN because it lacks a valid forwarding path. Proxy ARP does not influence route selection or next-hop resolution for the router's own forwarding decisions, so it is an irrelevant and incorrect fix.
- ✓
Change the static route on the HQ router to point to 10.0.0.2.
Why this is correct
Changing the static route on the HQ router to point to 10.0.0.2 is the correct fix because 10.0.0.2 is the branch router's interface address on the shared point-to-point link. The existing static route likely uses 10.0.0.1, which is the HQ router's own address, making the next-hop unreachable and causing the router to recursively look up its own interface, ultimately dropping the packets. Pointing to 10.0.0.2 gives the HQ router a valid, directly connected next-hop through which it can forward traffic toward the branch LAN, restoring end-to-end connectivity.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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