Which of the following statements regarding OSPF route-summarization commands are true?

Question

Options

• AThe abr-summary command is executed in the OSPF view.
• BThe abr-summary command is executed in the OSPF area view.
• CSpecify a mask for the network of the abr-summary command. That is, if not-advertise is not specified in the abr-summary command, the advertise parameter takes effect by default.
• DSpecify a mask for the network of the abr-summary command. That is, if advertise is not specified in the abr-summary command, the not-advertise parameter takes effect by default.

• A
  78% (29)
• B
  5% (2)
• C
  3% (1)
• D
  14% (5)

Explanation

Option A is correct because the abr-summary command is entered from within the OSPF process view (accessed via ospf [process-id]), not a sub-view - the command operates at the OSPF process level to configure inter-area route summarization on an ABR.

Option B is wrong because it places the command in the OSPF area view (a sub-mode entered via area [area-id]); while ABR summarization is related to areas, the command itself is issued one level up in the OSPF process view.

Options C and D both misstate the default advertise behavior: the correct default is that the summary route is advertised if neither keyword is specified, so C's wording is misleading and D's claim (that not-advertise is the default) is outright false - you must explicitly add not-advertise to suppress the summary.

Memory tip: Think of ABR summarization as a process-level policy - you're telling the OSPF process "here's how to summarize across all your areas," so the command logically lives in the OSPF view, not inside any individual area view. For the default behavior, remember "advertise unless told otherwise."

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