The output of a device viewing LSDB is shown in the figure. According to the content analysis in the figure, what information can we obtain? (Multiple choice)

Question

Options

• AThe LSA 10.1.0.4 has survived on this router for 875 seconds
• BRouter 4.4.4.4 belongs to Guiqian District City
• CRouter 4.4.4.4 belongs to the same LSDB with OSPF domain
• DRouter 1.1.1.1 belongs to the non-backbone area
• ERouter 2.2.2.2 is an ASBR, but does not belong to the same area as 4.4.4.4

• A
  72% (18)
• B
  12% (3)
• C
  16% (4)

Explanation

A is correct because every LSA entry in an OSPF LSDB output includes an "Age" field (in seconds) showing how long that LSA has resided in the database - if the figure shows Age = 875 for LSA 10.1.0.4, that value is directly readable. D is correct because the figure's LSDB output identifies the area associated with Router 1.1.1.1's Router LSA as a non-zero area ID, and in OSPF only Area 0 is the backbone - any other area is a non-backbone (stub, NSSA, or standard) area. E is correct because a Type 4 LSA (ASBR Summary LSA) advertising 2.2.2.2 is generated by an ABR to notify other areas about an ASBR that exists elsewhere; its very presence in this LSDB means 2.2.2.2 is an ASBR in a different area than 4.4.4.4.

B is wrong because OSPF LSDBs store only routing topology data (router IDs, link costs, area IDs, network prefixes) - geographic or administrative labels like city names are never encoded in OSPF. C is wrong because information about a router appearing in your LSDB does not mean that router is in your same area; Type 3 and Type 4 summary LSAs carry inter-area information into your LSDB about routers that live elsewhere.

Memory tip: Link LSA types to scope - Type 1/2 are local to one area, Type 3/4 cross area boundaries (Type 4 specifically flags ASBRs in other areas). When you see a Type 4 LSA for a router, it is definitionally in a different area than your viewing point.

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