150-230 · Question #203
Which OSPF LSA type is used by a DR in area 0 to distribute external routes to another area?
The correct answer is C. Type 5. See the full explanation below for the reasoning.
Question
Which OSPF LSA type is used by a DR in area 0 to distribute external routes to another area?
Options
- AType 3
- BType 4
- CType 5
- DType 7
How the community answered
(27 responses)- A7% (2)
- B19% (5)
- C70% (19)
- D4% (1)
Community Discussion
5
Anjali D.Dec 6, 2025I was ready to mark D because Type 7 kept coming to mind when I saw "external routes," but then someone in our group pointed out that Type 7 only lives inside NSSA areas and gets converted at the ABR, so since the question puts us squarely in area 0, the LSA flooding external routes across the domain is the Type 5, which is answer C. Anyone else get tripped up by the Type 7 connection here, or did you land on C right away?
Lena V.Dec 22, 2025Type 5 is right. The ASBR floods a Type 5 LSA domain-wide across all normal areas to advertise external routes, and it carries the actual external prefix with metric type and cost, which is exactly what the exam tests when it asks about inter-area external route distribution.
Anjali D.Dec 24, 2025Lena is spot on about Type 5 flooding domain-wide, though worth noting that Type 5s are actually blocked at ABRs bordering stub and totally stubby areas, which is exactly why those area types need a default route instead.
Bartosz H.Apr 22, 2026Type 5 is right, and it is worth burning into your brain that Type 5 LSAs are flooded domain-wide by the ASBR itself, not by the DR, and they cross area boundaries without the ABR converting them (unlike Type 3). Quick follow-up to make sure the concept is solid: do you know what happens to external route information when it originates inside a stub or NSSA area, and why Type 7 shows up in that scenario instead?
Yusuf A.Apr 24, 2026Right, and the way my senior described NSSA to me is that the area blocks Type 5s just like a stub area does but still needs to originate external routes locally, so the ASBR inside generates Type 7 instead, which stays confined to the NSSA until the ABR converts it to a Type 5 at the boundary for the rest of the domain to see.