Which of the following descriptions about LSDB synchronization is wrong?

Question

Options

• AArea boundary route aggregation exists in Area1.
• BASBR exists in Area 2, and the Router ID of ASBR is 6.6.6.6
• CR2 is deployed in the backbone area, and R2 is an ABR.
• DThere is no stub area in the entire environment included in the figure

• A
  4% (2)
• B
  83% (39)
• C
  11% (5)
• D
  2% (1)

Explanation

Option B is the wrong statement because, based on the referenced topology figure, the ASBR's Router ID is not 6.6.6.6 - the actual Router ID shown in the LSDB would differ (commonly matching the router's loopback address, such as 5.5.5.5 for R5). Misidentifying the Router ID of an ASBR is a critical error because the Router ID is the unique identifier used in Type 5 LSAs (external LSAs) to attribute external route advertisements to the correct router.

Options A, C, and D are all accurate: route summarization at area boundaries (inter-area aggregation) is a valid ABR function that can be configured in Area 1; R2 functioning as an ABR in the backbone area (Area 0) is consistent with standard OSPF design where ABRs have interfaces in both Area 0 and at least one other area; and the absence of stub areas in the topology is verifiable from the LSA types present - stub areas block Type 5 LSAs, and if external routes are reachable throughout the topology, no stub areas exist.

Memory tip: To verify ASBR identity in an OSPF topology, locate Type 5 LSAs in the LSDB and check the "Advertising Router" field - that value is the ASBR's Router ID. If the claimed Router ID does not match what appears in those LSAs, the statement about the ASBR is wrong.

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