JN0-106 Routing Fundamentals Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  The static route must have a lower preference than any dynamic route to the same prefix.

  Why it's wrong here

  Preference in Junos is a numeric priority that determines which route is selected when multiple protocols offer routes to the same destination prefix. However, route preference has no bearing on whether the next-hop address of a static route can be resolved; a static route can be installed even if it loses to a dynamic route on preference, as long as its own next-hop has an active route. Conversely, a static route with the best (lowest) preference will still be rejected if its next-hop is unreachable. Thus, lowering the static route's preference does not help satisfy the next-hop reachability requirement.

• ✗

  The next-hop must have an ARP entry in the ARP table.

  Why it's wrong here

  Juniper routers use ARP only to map an IP address on a directly connected subnet to a Layer 2 MAC address for actual frame forwarding. For the indirect next-hop 192.168.1.1, the router first performs a recursive lookup to find an active route to that address; the next-hop of that intermediate route — which may be on a different subnet — is the one that eventually requires ARP resolution. Therefore, an ARP entry for 192.168.1.1 may not exist at all, and its absence does not prevent the static route from being installed. What is mandatory is the presence of an active route to 192.168.1.1.

• ✓

  The next-hop 192.168.1.1 must be reachable via an active route (e.g., a direct or OSPF route).

  Why this is correct

  A static route with an indirect next-hop is installed in the Junos routing table only after the next-hop address is recursively resolved via a routing table lookup. In this case, 192.168.1.1 must be matched by an active route — such as a directly connected subnet, an OSPF route, or another static route — otherwise the static route to 10.0.0.0/8 is marked as unresolved and is not placed in the forwarding table. This resolution is required regardless of the static route's preference or metric. If the active route to the next-hop is removed, the static route is immediately hidden from the active route table.

• ✗

  The metric of the static route must be lower than that of any other route to the same prefix.

  Why it's wrong here

  Metric (cost) in Junos is a protocol-specific secondary tiebreaker used only when two routes from the same protocol share the same preference and go to the same prefix; it is never used during next-hop resolution of a static route. Static routes do not use metric at all in the default Junos configuration, and the static route's metric value if set does not influence whether 192.168.1.1 is reachable. The decision to install a static route depends on the route being active — meaning its next hop resolves — and on its preference relative to other routes to the same prefix. Hence, comparing metrics is irrelevant to the scenario described.

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