OSPF type 2 external routing cost is the sum of AS internal cost (cost from router to ASBR) and AS external cost.

Question

Options

• ATRUE
• BFALSE
• C
• D

• A
  8% (4)
• B
  78% (38)
• C
  10% (5)
• D
  4% (2)

Explanation

B is correct because OSPF Type 2 (E2) external routes use only the external cost assigned by the ASBR - the internal OSPF path cost to reach the ASBR is deliberately ignored. This makes E2 costs uniform across the entire OSPF domain regardless of how far a router is from the ASBR.

Why A is wrong: The description in the question - summing internal cost + external cost - actually defines Type 1 (E1) external routes, not Type 2. Swapping the two types is the classic trap here.

Memory tip: Think of it as "1 adds, 2 stays fixed." E1 adds the internal path cost on top of the external metric as the route propagates inward, making the metric grow. E2 stays fixed at just the external metric no matter where in the domain you are - hence Type 2 routes are the default in OSPF and are preferred when the external metric is already known to dominate.

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