Which of the following descriptions about Network-Summary-LSA is correct? (Multiple choice)

Question

Options

• AThe Metric in the Network-Summary-LSA is set to the cost value from the ABR to the destination network segment
• BThe Metric in the Network-Summary-LSA is set to the network mask of the destination network segment
• CNetwork-Summary-LSA is generated by ASBR
• DThe Link State ID in the Network-Summary-LSA is set to the IP address of the destination network

• A
  74% (26)
• B
  9% (3)
• C
  3% (1)
• D
  14% (5)

Explanation

Option A is correct because the Metric field in a Type 3 Network-Summary-LSA carries the cost the ABR has calculated to reach the destination network - this is what allows routers in other areas to compute inter-area path costs by adding their own cost to the ABR to this metric.

B is wrong because the network mask of the destination is stored in a separate Network Mask field, not in the Metric. Confusing these two fields is a classic distractor. C is wrong because Network-Summary-LSAs (Type 3) are originated by ABRs (Area Border Routers); ASBRs originate Type 5 AS-External-LSAs to advertise routes learned from outside the OSPF domain. D is wrong because the Link State ID holds the network address (the network prefix) of the destination, not a generic "IP address" - the distinction matters because the network address paired with the separate Network Mask field fully describes the destination prefix.

Memory tip: Think "ABR = Summary, ASBR = External" for LSA types, and remember the Metric always means cost in OSPF - never a mask, never an address. If you can anchor those two rules, you can eliminate C and B instantly and reason through A and D confidently.

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