From a design perspective which two of the following OSPF statements are most relevant? (Choose two)

Question

Options

• AOSPF stub areas can be thought of as a simple form of summarization
• BOSPF cannot filter intra-area routes
• CAn ABR can only exist in two areas - the backbone and one adjacent area
• DPerformance issues in the Backbone area can be offset by allowing some traffic to transit a non-
• EThe size of an area (the LSDB) will be constrained by the size of the IP MTU

• A
  81% (29)
• C
  3% (1)
• D
  11% (4)
• E
  6% (2)

Explanation

OSPF stub areas block Type 5 (external) LSAs and replace them with a single default route from the ABR, effectively summarizing all external destinations into one prefix-making them a simple summarization tool (A). This is a critical design insight for reducing LSDB size in remote or branch areas. OSPF's link-state nature requires all routers within an area to have an identical LSDB, so intra-area routes (Type 1 and Type 2 LSAs) cannot be filtered-they flood to every router in the area unconditionally (B). This design constraint means filtering can only be applied at area boundaries (ABRs) for inter-area routes. Statement C is false (ABRs can belong to the backbone plus multiple non-backbone areas). Statement E is false (area size is constrained by CPU and memory, not MTU).

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