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.

• ✓

  First configure match conditions, then configure the action, and finally apply the filter to the interface.

  Why this is correct

  This is correct because you must define what traffic to match (from clause) and what action to take (then clause) before applying the filter to an interface. Applying the filter without a complete term would result in an incomplete configuration.

• ✗

  First apply the filter to the interface, then configure match conditions, then configure the action.

  Why it's wrong here

  Attempting to apply a filter to an interface before the filter has been created in the configuration hierarchy results in a commit error, because Junos requires that the filter name referenced under 'interface ... family ... filter input/output' already exists with a defined term. Even if you pre-created an empty filter, the application would fail validation until the filter has a complete term. Thus, the filter definition must precede its application to an interface.

• ✗

  First configure the action, then configure match conditions, then apply the filter to the interface.

  Why it's wrong here

  This is incorrect because the action (then clause) is meaningless without match conditions. In Junos, the term is structured as 'from' (match) then 'then' (action); setting action first does not cause a syntax error but is logically backwards.

• ✗

  First configure match conditions, then apply the filter to the interface, then configure the action.

  Why it's wrong here

  Configuring match conditions and then applying the filter to an interface while omitting the 'then' action leaves the filter term incomplete; Junos would either apply the default action of 'accept' or refuse to commit depending on the configuration context, but in either case the filter does not perform the intended security policy. Explicitly configuring the action ensures the filter has a deterministic behavior before it is attached to a live interface. So the action must be defined before the interface binding.

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