An engineer needs to prevent Type 4 and Type 5 LSAs from entering a specific OSPF area while still allowing external routes to be summarized via default routing. Which area type should be configured?
Trap 1: Standard OSPF Area
Incorrect. A standard area floods all LSA types including Type 4 and 5.
Trap 2: Not-So-Stubby Area (NSSA)
Incorrect. An NSSA allows external routes via Type 7 LSAs to be redistributed within it, rather than blocking all external routing information.
Trap 3: Standard Stub Area
Incorrect. A standard stub area blocks Type 4 and 5 LSAs but still permits inter-area Type 3 summary LSAs.
- A
Standard OSPF Area
Why it fails: Incorrect. A standard area floods all LSA types including Type 4 and 5.
- B
Not-So-Stubby Area (NSSA)
Why it fails: Incorrect. An NSSA allows external routes via Type 7 LSAs to be redistributed within it, rather than blocking all external routing information.
- C
Totally Stubby Area
Correct. A totally stubby area blocks Type 3, 4, and 5 LSAs and uses a default route for external destinations.
- D
Standard Stub Area
Why it fails: Incorrect. A standard stub area blocks Type 4 and 5 LSAs but still permits inter-area Type 3 summary LSAs.