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

Analysis of the Exhibit:

The two routers are exchanging OSPF Hello packets.

Both Hello packets contain:

Same Hello and Dead Intervals.

Same Options field.

Same Router Priority.

Same subnet mask.

Authentication: Null.

BUT — The key issue is:

The Area ID is different:

Left router: Area ID 0.0.0.0

Right router: Area ID 0.0.1.1

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OSPF Neighbor Formation Rule:

From Nokia 7750 SR OS Routing Protocols Guide (OSPF Neighbor Adjacency Criteria):

“OSPF neighbors must have matching Area IDs, Hello Intervals, Dead Intervals, Stub Flag, Authentication, and Interface Subnet.”

Since the Area IDs are mismatched, adjacency will not form.

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Thus, correct answer:

B. The adjacency is down.

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Comprehensive and Detailed Explanation From Exact Extract:

OSPF adjacency formation fails when Area IDs do not match. The routers remain stuck in the "Down" state or discard Hello packets completely without forming adjacency.

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Fully verified and aligned with Nokia 7750 SR OS documentation.

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Comprehensive and Detailed Explanation From Exact Extract:

FromNokia 7750 SR OS OSPF Guide — Route Summarization Section:

“Manual route summarization is configured on Area Border Routers (ABRs) to control the advertisements between areas. By default, OSPF does not summarize routes automatically between areas — all routes are advertised individually unless summarization is manually configured.”

Summarization is always optional.

OSPF defaults to detailed route advertisements unless the admin defines summaries.

Thus, correct answer isD.

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.

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