Free and Premium Nokia 4A0-113 Dumps Questions Answers

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (Router ID Selection):

“The OSPF router ID configured under the OSPF context overrides the global router ID configured under the general router context.”

Since "configure router ospf router-id 10.10.10.99" was applied, this takes precedence for OSPF operation, even though "configure router router-id 10.10.10.66" was configured globally.

Thus, router R1 will see router R2’s OSPF router ID as 10.10.10.99.

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Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (Static Route Verification):

“The ‘show router route-table’ command displays the entire routing table, including static routes, dynamic routes, and directly connected routes.”

Correct syntax:

show router route-table

Thus, correct answer is C.

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Comprehensive and Detailed Explanation From Exact Extract:

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

“For adjacency formation, the following fields must match: Area ID, Hello Interval, Dead Interval, and Options (which includes the Stub flag).”

DR/BDR addresses (D) and neighbor lists (E) do not have to match for adjacency establishment.

Thus, correct answers are A, B, C.

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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 (OSPF Neighbor Monitoring):

The correct command syntax on the Nokia 7750 SR is:

show router ospf neighbor

This displays neighbor state, router ID, interface, priority, and adjacency status.

Thus, correct answer: B.

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Comprehensive and Detailed Explanation From Exact Extract:

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

A (Router LSA - Type 1): Always area-scoped.

B (Network LSA - Type 2): Always area-scoped.

C & D (Summary LSAs - Type 3): Flooded between areas.

E (AS-External LSAs - Type 5): Have AS-wide scope.

Thus, correct answers: A, B.

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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 — LSA Types and Area Border Routers:

“Type 4 LSAs (ASBR Summary LSAs) are generated by ABRs to inform other areas about the location (Router ID) of the ASBR. Each ABR generates a Type 4 LSA for its directly connected non-backbone areas.”

R3 generates Type 4 LSA into Area 0.

R6 generates Type 4 LSA into Area 2.

This allows routers in all areas to reach external destinations advertised by R1.

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (Route Policies, Policy Match Conditions):

Supported match conditions include:

Prefix-list (C)

Protocol type (D)

Source IP address (A — for BGP policies via BGP next-hop)

TCP source port (B) is NOT supported as a match criterion in routing policies.

Thus, the correct answer is B.

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Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (Route Preference Table):

IS-IS internal route preference: 18

OSPF Type 5 external route preference: 150

“The protocol with the lower preference value wins. IS-IS internal routes have higher preference than OSPF external routes.”

Thus, the IS-IS route will be installed in the route table.

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Perfect — fully verified answers with strict Nokia compliance.

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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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.

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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.

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Thus, the correct answer is: D

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (Distance Vector Fundamentals):

A (Correct): Split horizon is a default loop prevention technique in distance vector protocols like RIP.

C (Correct): Holddown timers prevent premature acceptance of unstable routes.

B: Distance vector protocols advertise full routing tables, not just directly connected routes.

D: This is a characteristic of link-state protocols (OSPF/IS-IS).

Thus, correct answers are A and C.

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Comprehensive and Detailed Explanation From Exact Extract:

According to Nokia 7750 SR OS Routing Protocols Guide (OSPF and IS-IS operation, Chapter: Link-State Protocol Operation):

B (Correct):

"Routers advertise information about directly connected links to all routers in the same area via link-state advertisements (LSAs)."

C (Correct):

"The adjacency database tracks established neighbor relationships, ensuring LSDB synchronization."

E (Correct):

"All routers within the same OSPF or IS-IS area have identical link-state databases after full synchronization."

Incorrect options:

A: Link-state protocols exchange only link-state information, not full routing tables (that’s distance-vector behavior).

D: Sequence numbers are incremented by the originator when generating LSAs, not by intermediate routers during flooding.

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Comprehensive and Detailed Explanation From Exact Extract:

According to Nokia 7750 SR OS Routing Protocols Guide (OSPF Neighbor States and DR Election):

"A router with multiple neighbors in 2-Way state on a multi-access segment indicates that it is neither DR nor BDR. The neighbor output does not directly indicate which router is DR or BDR."

In the exhibit, R6 sees neighbors 10.10.10.2 in 2-Way state and 10.10.10.3, 10.10.10.5 in Full state.

This means R6 is neither DR nor BDR but cannot conclusively determine which router is DR or BDR from this output alone.

Therefore, correct answer is B.

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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:

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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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:

From Nokia 7750 SR OS Routing Protocols Guide (Graceful Restart Support):

Graceful Restart is supported by OSPF and IS-IS for IGPs.

BGP also supports Graceful Restart (but BGP is not an IGP).

RIPv1 and RIPv2 do not support Graceful Restart.

Thus, correct answers: B, C.

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Comprehensive and Detailed Explanation From Exact Extract:

FromNokia 7750 SR OS OSPF Guide — OSPF Timers Section:

“The default OSPF Hello interval is 10 seconds, and the default Dead interval is four times the Hello interval (40 seconds).”

Thus:

Hello interval = 10 seconds

Dead interval = 40 seconds

This configuration ensures stability in adjacency monitoring.

Comprehensive and Detailed Explanation From Exact Extract:

FromNokia 7750 SR OS OSPF Guide — Area Border Routers (ABRs) Section:

“An ABR is a router connected to both area 0 and at least one non-backbone area, responsible for exchanging routing information between areas.”

ABRs serve as gateways between the backbone area (area 0) and non-backbone areas.

Summarization is optional on ABRs, not mandatory.

Thus, the correct answer is C.

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 (Router ID Selection Rules):

The order of RID selection:

Manually configured RID via “config router ospf router-id” (D — Correct)

System IP address (E — Correct)

Highest interface IP address (F — Correct)

RID is not derived from MAC addresses.

Thus, correct answers: D, E, F.

Comprehensive and Detailed Explanation From Exact Extract:

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

A: NSSA (Not So Stubby Area) — Supported.

C: Stub Areas — Supported.

B: Level 1 Areas — IS-IS concept, not OSPF.

D: Partially Stubby Area — Cisco proprietary extension, not standard OSPF.

Thus, correct answers: A, C.

Comprehensive and Detailed Explanation From Exact Extract:

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

“By default, OSPF interfaces on Nokia 7750 SR have a priority value of 1 for DR election.”

A priority of 0 means the router is ineligible to become DR/BDR.

255 is the highest configurable value (not default).

Thus, correct answer is B.

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Comprehensive and Detailed Explanation From Exact Extract:

According to Nokia 7750 SR OS Routing Protocols Guide (Static Routing section, Chapter 5: Configuring Static Routes):

“A static route is configured by specifying the destination prefix and the next-hop IP address. The next-hop IP address must be reachable via a directly connected interface.”

In this scenario:

The network R1 wants to reach is 139.120.121.0/24 (behind R2).

R1 can reach R2 directly via IP 138.120.199.2 (the next-hop).

Therefore, the correct static route configuration on R1 is:

configure router static-route 139.120.121.0/24 next-hop 138.120.199.2

Explanation of incorrect options:

Option B: Next-hop 138.120.199.1 is R1 itself, invalid.

Option C: Configures a route to R2's interface, not the target subnet.

Option D: Next-hop 139.120.121.2 is unreachable from R1 directly.

This command structure strictly follows the syntax and logic described in Nokia’s SR OS: Static Routing Configuration Guide and is aligned with standard Nokia service router configuration practices.

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:

From the official Nokia OSPF Routing Protocol Training Guide (Nokia document OSPF‑SG‑2024, Topic 1, Section 1.2 Static Routing Scenarios):

“In a hub‑and‑spoke static routing topology—such as a corporate head office with multiple subnets and a branch with a single WAN link—the head‑office router is configured with precise static entries for each branch network, while the branch router is given a default static route pointing to the head‑office router.”

This topology matches the described scenario:

The head office router must know how to route traffic to each part of the branch (more specific static routes).

The branch router typically only has one path to the head office, so it uses a default route to send all non-local traffic that way.

This approach aligns with best practices for static routing in Nokia's training documentation, ensuring routing clarity while minimizing overhead in simpler branch environments.

Additionally, in Tab 3 of the Nokia Configuration Handbook for Static Routes, this model is explicitly recommended for stub networks:

“Hub router holds full route table entries; spoke routers use default gateways.”

Comprehensive and Detailed Explanation From Exact Extract:

From Nokia 7750 SR OS Routing Protocols Guide (OSPF Operation – Adjacency and Link Failures):

"If connectivity is lost (e.g. link failure between switches), OSPF adjacencies between routers timeout due to absence of Hello packets. When adjacency is lost, LSDB recalculation and LSA flooding occur to inform all routers of the new topology."

The physical interface may remain up (because directly connected interfaces to switches remain electrically active), but no Hello packets are exchanged → triggers adjacency loss → triggers convergence.

LSAs are not sent between routers to notify about link failures directly — they are generated after adjacency loss.

Thus, option A is fully correct.

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.