4A0-113 Exam Dumps : Nokia OSPF Routing Protocol Exam

Comprehensive and Detailed Explanation From Exact Extract:

FromNokia 7750 SR OS OSPF Guide — OSPF Neighbor State Machine Section:

“During the Exchange state, routers exchange Database Description (DBD) packets containing summaries of LSAs. Sequence numbers and flags are used to coordinate this exchange.”

Both routers are sendingDR_DESC (Database Description)packets.

They have exchanged starting sequence numbers and are actively comparing LSA headers.

Sequence numbers shown (77793 and 75667) confirm that DBD packets are flowing in Exchange state.

Thus, correct answer isB.

Let’s break it down step-by-step:

Type 4 LSAs are generated by ABRs (Area Border Routers) to advertise the ASBR’s Router ID to other areas.

The ASBR itself (R1) does not generate Type 4 LSAs.

R1 belongs to Area 1.

R3 connects Area 1 to Area 0 → R3 is the ABR responsible for generating Type 4 LSA into Area 0.

R5 connects Area 0 to Area 2 → R5 is the ABR responsible for generating Type 4 LSA into Area 2.

Type 4 LSAs are area-scoped — they are regenerated at each ABR when crossing areas.

—

Now let’s analyze the options:

A — Incorrect: R1 (the ASBR) does not generate Type 4 LSAs.

B — Incorrect: R3 does not flood into all areas.

C — Incorrect: R3 does not flood into Area 2.

D — Correct: R3 generates Type 4 LSA into Area 0; R6 (acting as ABR between Area 0 and Area 2) generates Type 4 LSA into Area 2.

—

Thus, the correct answer is: D

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (OSPFv3 LSA Types):

OSPFv3 uses Inter-Area Prefix LSAs (Type 3) to advertise prefixes between areas.

R4 originates a Router LSA with its local prefixes into Area 0.

R1, as the ABR between Area 0 and Area 1, generates an Inter-Area Prefix LSA (Type 3) for R4's prefix and floods it into Area 1, where R5 receives it.

Thus, correct answer: D.

—