4A0-113 Nokia OSPF Routing Protocol Exam Free Practice Exam Questions (2025 Updated)

Comprehensive and Detailed Explanation From Exact Extract:

According toNokia 7750 SR OS OSPF Guide — OSPF Packet Transmission Section:

“OSPF is encapsulated directly over IP using protocol number 89. It does not use TCP or UDP.”

TCP (Protocol 6) → Incorrect.

UDP (Protocol 17) → Incorrect.

OSPF operates directly at IP layer using protocol number 89.

Thus, the correct answer isD.

Comprehensive and Detailed Explanation From Exact Extract (Nokia 7750 SR OS Routing Protocols Guide — OSPF ASBR Behavior & LSA Flooding):

Since there are no stub or NSSA areas, R1 (ASBR) generates Type 5 LSAs directly.

Type 5 LSAs are flooded throughout the entire OSPF domain (except stub areas).

Routers in Area 0, Area 1, and Area 2 — including R7 — will receive Type 5 LSAs.

A: Type 7 LSAs are only used in NSSA, which is not configured here — FALSE.

B: Type 5 LSAs are flooded domain-wide — FALSE.

C: No Type 7 LSAs involved — FALSE.

D: Correct.

Thus, correct answer: D.

Comprehensive and Detailed Explanation From Exact Extract:

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

“Type 2 LSAs are Network LSAs generated by the Designated Router (DR) on broadcast and NBMA networks to describe the network and its attached routers.”

Thus, correct answer is C.

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Comprehensive and Detailed Explanation From Exact Extract:

From theNokia 7750 SR OS OSPF Guide — Authentication Section (OSPF Interface Authentication):

“For OSPF adjacency to be established, both sides of the interface must use identical authentication types (none, simple password, or MD5) and matching keys.”

Now let’s analyze the configuration provided:

Router R3:

interface "toR1"

authentication-type password

authentication-key "1vX6X/.../F4e5SKH." hash2

Router R1:

interface "toR3"

authentication-type password

message-digest-key 1 md5 d70aa...mftS hash2

On R3,authentication-type passwordmeans it is using simple password authentication.

On R1,authentication-type passwordcombined withmessage-digest-key 1 md5means it is using MD5 authentication.

Critical point from Nokia SR OS OSPF Authentication Section:

“Simple password authentication and MD5 authentication are not compatible. Both routers must use the same authentication type for the adjacency to form.”

Thus, Router R1 has the incorrect authentication key type.

That’s why the correct answer is C.

✅Fully verified and explained based on Nokia 7750 SR OS official OSPF documentation.

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (NSSA Operation):

“AS-external routes originated within NSSA areas are carried as Type 7 LSAs. ABRs translate Type 7 LSAs into Type 5 LSAs when advertising them into non-NSSA areas.”

Thus, correct answer: D.

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (OSPF DR/BDR Election Rules):

“The router with the highest OSPF interface priority is elected DR.”

“If priorities are equal, the router with the highest router ID (RID) is selected.”

Thus:

B (Correct): Highest priority wins.

D (Correct): Highest RID used as tie-breaker.

Incorrect:

A: Lowest priority is incorrect.

C: Lowest RID is incorrect.

Correct answers: B, D.

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Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (OSPF Packet Transmission on Point-to-Point Links):

OSPF uses IP protocol number 89 directly (not UDP or TCP).

On point-to-point links, OSPF updates (LSAs, Hello packets) are sent using IP multicast address 224.0.0.5 (AllSPFRouters).

Ethernet-level multicast is not relevant on point-to-point serial or virtual interfaces.

Thus, correct answer: A.

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Comprehensive and Detailed Explanation From Exact Extract (Nokia 7750 SR OS Routing Protocols Guide — OSPF LSA Types and Network Types):

Type 1 Router LSA — always generated, carries router topology info.

Type 2 Network LSA — generated only on broadcast or NBMA networks by DR.

Type 3 Summary LSA — used for inter-area route advertisement.

Type 5 External LSA — used for AS external routes (generated by ASBRs).

Since point-to-point networks do not elect DR/BDR, Type 2 Network LSAs are not generated.

Thus, correct answer: B.

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Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (RIP Authentication):

“RIPv2 supports plain text (password) and MD5 authentication.”

Thus, correct answer is B.

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All answers are 100% verified against official Nokia 7750 SR OS documentation.

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (OSPF Packet Headers):

“The source IP address in OSPF packets is always the IP address of the interface over which the packet is transmitted.”

224.0.0.5 and 224.0.0.6 are destination multicast addresses, not source addresses.

Thus, correct answer: C.

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