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.

• ✗

  Configure a static route for 203.0.113.0/24 with a lower preference.

  Why it's wrong here

  Configuring a static route with a lower preference (administrative distance) for 203.0.113.0/24 would install it in the routing table ahead of the OSPF route, because lower preference values are preferred. This overrides OSPF's dynamic path selection entirely, meaning the router no longer follows OSPF's cost-based decisions or reacts to OSPF topology changes. A static route does not monitor OSPF neighbor state or link health, so if the designated interface fails, the statically routed traffic will be blackholed or fail to failover, eliminating the redundancy that OSPF is supposed to provide.

• ✓

  Set the OSPF metric on the backup interface to a higher value.

  Why this is correct

  In OSPF, the metric (cost) determines the preference of a route: lower total cost wins. By configuring a higher metric on the backup interface, the backup path's total cost becomes larger, so OSPF installs the lower-cost primary path in the forwarding table. The backup path remains in the OSPF database and is immediately used if the primary path disappears, preserving dynamic failover. This is the standard method to create an active/backup topology while keeping OSPF's adaptive behavior intact.

• ✗

  Use policy-options to set a higher preference for one of the paths.

  Why it's wrong here

  Junos route preference is a protocol-level value, not a per-path attribute; OSPF routes share one preference, so a policy that raises preference for one OSPF route would apply to all OSPF routes or require complex matching that still doesn't reflect OSPF's cost. Altering preference via policy-options changes how the routing table compares OSPF with other protocols, not how OSPF selects among its own paths. OSPF already has a built-in mechanism, the metric, to differentiate paths, so trying to manipulate preference per interface is both the wrong tool and ineffective for creating a primary/backup relationship.

• ✗

  Modify the load-balance configuration under forwarding-options.

  Why it's wrong here

  Load balancing under forwarding-options controls how traffic is spread across multiple equal-cost next hops, such as per-flow or per-packet distribution. It only activates when the routing table has two or more routes with identical preference and metric; a backup interface with a higher OSPF metric is not equal-cost, so load balancing would never split traffic to it. Configuring load balancing does nothing to change the OSPF metric or preference, so it cannot designate one path as primary and the other as backup. This option would at best cause the router to alternate traffic across both paths if they were equal-cost, which is the opposite of the desired active/backup behavior.

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