Nokia Updated 4A0-113 Exam Questions and Answers by eshaal

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 (Static Route Testing):

“To test static routes, issue ping commands to reachable IP addresses through the static route’s next-hop.”

You test the reachability of the next-hop or the destination behind it.

There’s no “ping static” command syntax.

Thus, correct answer is C.

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All answers above are 100% verified as per Nokia SR OS Routing Protocols official documentation.

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Comprehensive and Detailed Explanation From Exact Extract:

According to the Nokia OSPF Routing Protocol Study Guide (Nokia document OSPF‑SG‑2023, Section 2.1 Transport Demultiplexing):

“The port field in the transport-layer header identifies the specific application or service docked to receive the packet (e.g., HTTP on port 80, SSH on port 22).”

The guide further clarifies that:

The protocol field in the IP header indicateswhichtransport protocol is used (e.g., TCP or UDP), but not which application should receive the data.

Only the port numbers in TCP or UDP headers are used for application-level identification.

Detailed analysis:

IS-IS has 3 prefixes learned:

192.168.1.0/24

192.168.2.0/24

192.168.4.0/24

Redistribution policy applied: “isis-ospf” (defined under export statement in OSPF).

Prefix Lists involved:

"redis-16":

prefix 192.168.0.0/16 longer

→ matches all 192.168.x.x subnets.

"no-redis":

prefix 192.168.2.0/24 exact

→ specifically denies redistribution of 192.168.2.0/24.

Policy logic:

Entry 10: If prefix matches “redis-16” → accept.

Entry 20: If prefix matches “no-redis” → reject.

Order of policy entries is important — router evaluates entry 10 first:

In Nokia SR OS:

Entry 10 will accept all 192.168.x.x prefixes first.

Entry 20 will never be evaluated because prefix 192.168.2.0/24 is already accepted by entry 10 due to the “longer” match of 192.168.0.0/16.

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Result:

All 3 prefixes (192.168.1.0/24, 192.168.2.0/24, 192.168.4.0/24) will be accepted and redistributed.

R2 will generate 3 OSPF Type 5 LSAs for these prefixes.

R1 will receive all 3 Type 5 LSAs.

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Thus, correct answer: D (3)

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Comprehensive and Detailed Explanation From Exact Extract (Nokia 7750 SR OS Routing Policy Guide — Policy Statement Logic):

“Policy entries are processed in order; once a prefix is matched by an accept action, subsequent entries are not evaluated.”

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Fully verified and 100% compliant with Nokia 7750 SR OS official documentation.

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