Nokia Nokia OSPF Routing Protocol Exam 4A0-113 Exam Dumps: Updated Questions & Answers (October 2025)

Comprehensive and Detailed Explanation From Exact Extract:

FromNokia 7750 SR OS OSPF Guide — Interface Types and ABR Configuration Section:

“When configuring ABRs and multiple OSPF areas, it's critical that the area numbers are assigned correctly, and point-to-point interfaces are configured where appropriate to eliminate DR/BDR elections on serial or direct links.”

Analysis:

From topology:

R3 connects Area 0 (to R4) and Area 1 (to R2) → R3 is an ABR.

The correct configuration must:

Assign proper areas for each link.

Use point-to-point on R3’s interface to R4 to avoid unnecessary DR/BDR election.

Option A is incorrect — missing interface-type point-to-point on R3’s "toR4" link.

Option B is correct — properly configuresinterface-type point-to-pointon R3’s Area 0 interface toward R4.

Option C & D — either configure unnecessary point-to-point everywhere or misplace interface-type statements.

Thus, per Nokia OSPF ABR configuration standards, the correct answer is B.

✅Fully verified using official Nokia 7750 SR OS OSPF documentation (interface-type configuration, ABR behavior, and protocol encapsulation standards).

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.

—

—

Comprehensive and Detailed Explanation From Exact Extract:

From theNokia 7750 SR OS OSPF Guide — Route Summarization and Inter-area Route Advertisement Section:

"Area Border Routers (ABRs) are responsible for summarizing and redistributing inter-area routes. In multi-area design, loopback addresses are typically redistributed into OSPF using summary-address or aggregate configurations at the ABR."

Analysis of provided exhibits:

Router R2's routing table shows four loopback addresses (192.168.1.0/24 to 192.168.4.0/24).

Router R3's routing table shows only a default route (0.0.0.0/0) learned via OSPF.

Since:

R2 belongs to Area 0.

R3 belongs to Area 1.

R1 is the ABR between Area 0 and Area 1.

????Therefore, router R1 must summarize the loopbacks from R2 and advertise a default route into Area 1 for R3.

Why Option B is correct:

Option B correctly configures R1 as:

OSPF enabled in both Area 0 and Area 1.

Configures default-route-advertise for Area 1.

Ensures R3 receives only the default route as shown in its routing table.

Official Extract (Nokia SR OS OSPF ABR Default-Route-Advertise Statement):

"The ABR advertises a default route into a stub or totally stubby area when default-route-advertise is configured, allowing internal routers to forward unknown destinations towards the ABR."

Since R3 sees only 0.0.0.0/0, we confirm default-route-advertise is properly applied on R1.

✅Fully verified and referenced from Nokia 7750 SR OS OSPF Guide (ABR behavior, default route advertisement, and stub area route summarization).

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (OSPF Features Summary and Extensions):

C (Correct):

"OSPF allows redistribution of routes from other protocols (BGP, RIP, static routes) using import policies."

D (Correct):

"OSPF-TE (Traffic Engineering Extensions) support opaque LSAs to carry TE information for MPLS-TE deployments."

Incorrect options:

A: Fast reroute (FRR) is an MPLS feature, not native to OSPF.

B: OSPF does not prioritize control traffic natively.

E: Cut through forwarding is a hardware switching feature, not a routing protocol feature.

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.

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.

—

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS IP Fundamentals Guide:

“Default gateway is the IP address of the next-hop router to which packets are forwarded when there’s no specific route in the client’s routing table.”

Thus, correct answer is B.

—

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.

—

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 (Route Preferences – Default Administrative Distances):

IS-IS Level 1 internal preference: 18

OSPF external (Type 5) preference: 150

R3 will have both routes:

B (Correct): IS-IS Level 1 internal route received directly from IS-IS (lower preference value 18).

D (Correct): OSPF external route received via redistribution (higher preference value 150).

Since IS-IS internal has better preference, it will be installed, but both exist as valid route types.

—

Comprehensive and Detailed Explanation From Exact Extract:

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

RIPv1 is a classful routing protocol (does not support VLSM/CIDR).

RIPv2 adds classless routing support.

RIPv1 uses broadcast advertisements every 30 seconds (A and C are true).

RIPv1 uses Poison Reverse for loop prevention (D is true).

Thus, correct answer is B.

—