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100+ Free Nokia IS-IS Routing Protocol Practice Questions

Pass your Nokia IS-IS Routing Protocol (4A0-112) exam on the first try — instant access, no signup required.

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A Nokia 7750 SR is configured as L1-only in an area with a single L1L2 attachment. The L1L2 router fails. What does the L1-only router do?

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Key Facts: Nokia IS-IS Routing Protocol Exam

40

Exam Questions

Nokia 4A0-112 exam profile

90 min

Exam Duration

Nokia 4A0-112 exam profile

70%

Passing Score

Nokia SRC scoring policy

$125

Exam Fee (USD)

Pearson VUE Nokia pricing

Pearson VUE

Test Provider

Nokia SRC delivery partner

3 years

Credential Validity

Nokia SRC recertification policy

Nokia 4A0-112 (IS-IS Routing Protocol) is a 40-question, 90-minute Pearson VUE multiple-choice exam with a 70% passing score and a $125 USD fee. It validates specialist knowledge of IS-IS - ISO 10589 fundamentals, NET addressing, the four PDU types (IIH/LSP/CSNP/PSNP), L1/L2 areas with DIS election, LSDB flooding and Dijkstra SPF, route leaking with the RFC 2966 down bit, wide metrics, multi-topology IPv6, and IS-IS configuration on Nokia SR OS including Segment Routing sub-TLVs and BFD/LFA convergence. The credential is part of the Nokia SRC program and stays valid for 3 years.

Sample Nokia IS-IS Routing Protocol Practice Questions

Try these sample questions to test your Nokia IS-IS Routing Protocol exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which standards body originally specified the IS-IS routing protocol that RFC 1195 later extended to support IP?
A.IETF in RFC 1058
B.ISO in standard 10589
C.IEEE in 802.1D
D.ITU-T in G.984
Explanation: IS-IS was originally developed by ISO as the intra-domain routing protocol for the OSI Connectionless Network Service (CLNS) and is published as ISO/IEC 10589. RFC 1195 (Integrated IS-IS) later extended it to carry IPv4 reachability so the same protocol could route both CLNS and IP.
2IS-IS PDUs are encapsulated directly inside which layer of the protocol stack?
A.Inside IP packets, like OSPF
B.Inside TCP segments on a well-known port
C.Directly in the data link layer (no IP header)
D.Inside UDP datagrams on port 520
Explanation: IS-IS PDUs are encapsulated directly in Layer 2 frames and do not ride inside IP. On Ethernet they use LLC/SNAP with an IS-IS protocol identifier, on point-to-point links they use HDLC/PPP. Because they are not in IP packets, IS-IS is generally regarded as harder to attack remotely than OSPF.
3What does CLNS, the network-layer service that IS-IS was originally written for, stand for?
A.Cellular Lightweight Network Stack
B.Connectionless Network Service
C.Class-based Layer Network Service
D.Carrier Loop Negotiation System
Explanation: CLNS stands for Connectionless Network Service. It is the OSI equivalent of IPv4 unicast service: a datagram, best-effort, connectionless network layer specified by ISO. IS-IS was designed to route CLNP (the CLNS protocol), and Integrated IS-IS extended it to also carry IPv4 reachability.
4An IS-IS Network Entity Title (NET) is composed of which three concatenated parts?
A.Country code, AS number, and router ID
B.Area address, system ID, and NSEL
C.Network ID, host ID, and checksum
D.Domain ID, neighbor ID, and metric
Explanation: A NET is a special NSAP that identifies the routing process itself. It is built as area-address + system-ID + NSEL, where the NSEL must be 0x00 to indicate the local system (an IS, not a service on it). The system-ID is 6 bytes; the area address is variable (1-13 bytes) but typically 1-3 bytes.
5How many bytes long is the IS-IS system ID on Nokia SR OS and most other modern implementations?
A.2 bytes
B.4 bytes
C.6 bytes
D.8 bytes
Explanation: The IS-IS system ID is fixed at 6 bytes (12 hex digits). It must be unique within the routing domain. Operators frequently derive it from a router loopback IPv4 address or from a chassis MAC address to guarantee uniqueness.
6A Nokia 7750 SR is configured with the NET 49.0001.0100.1001.5005.00. Which substring represents the area address?
A.49.0001
B.0100.1001.5005
C.00
D.5005.00
Explanation: Reading the NET right to left, the trailing 00 is the NSEL, the next 6 bytes 0100.1001.5005 are the system ID, and everything in front is the area address. Here the area is 49.0001 (the AFI 49 plus the area bytes 0001), the system ID is 0100.1001.5005, and the NSEL is 00.
7Which AFI value is most commonly used for IS-IS area addresses in private IP networks (similar to how RFC 1918 defines private IPv4 space)?
A.0x39 (E.164)
B.0x47 (ISO 6523-ICD)
C.0x49 (private/local)
D.0xC0 (IETF reserved)
Explanation: AFI 49 is the OSI equivalent of RFC 1918 private space; it is reserved for local/private use and is what most operators put at the front of their IS-IS area addresses. Public NSAP allocations would use other AFI values such as 39 or 47, but those are rare in modern IS-IS-for-IP deployments.
8Which four IS-IS PDU types are defined in ISO 10589?
A.Hello, Update, Query, Reply
B.IIH, LSP, CSNP, PSNP
C.OPEN, UPDATE, NOTIFICATION, KEEPALIVE
D.DBD, LSR, LSU, LSAck
Explanation: ISO 10589 defines four PDU types used by IS-IS: IIH (IS-IS Hello) for adjacency formation, LSP (Link State PDU) carrying topology and reachability, CSNP (Complete Sequence Number PDU) summarizing the LSDB, and PSNP (Partial Sequence Number PDU) used to acknowledge or request specific LSPs.
9Which IS-IS PDU type carries the actual topology and prefix information that builds the link-state database?
A.IIH
B.LSP
C.CSNP
D.PSNP
Explanation: Link State PDUs (LSPs) carry the originator's adjacencies, IP prefixes, and other TLVs. They are flooded throughout the level and stored in the link-state database (LSDB). IIHs build adjacencies; CSNPs and PSNPs synchronize the database but do not themselves carry the topology data.
10On a Nokia 7750 SR with default IS-IS timers, how often does a router send an IIH on a LAN interface and what is the default hold time?
A.1 second hello / 4 second hold
B.3 seconds hello / 9 second hold
C.10 seconds hello / 30 second hold
D.30 seconds hello / 120 second hold
Explanation: Nokia SR OS uses the standard IS-IS defaults: a hello-interval of 10 seconds and a hold-time (multiplier 3) of 30 seconds for non-DIS routers. The DIS sends hellos three times more frequently to keep the pseudonode information up to date on a LAN.

About the Nokia IS-IS Routing Protocol Exam

The Nokia IS-IS Routing Protocol exam (4A0-112) is a specialist credential in the Nokia Service Routing Certification (SRC) program. It validates deep knowledge of the IS-IS link-state routing protocol as standardized in ISO 10589 and extended for IP by RFC 1195 - including PDU types (IIH, LSP, CSNP, PSNP), Level 1 / Level 2 areas, Designated IS election, LSP flooding and database synchronization, Dijkstra SPF and partial route calculation, route leaking (RFC 2966), wide metrics (RFC 5305), IPv6 (RFC 5308) and multi-topology (RFC 5120), authentication (RFC 5304/5310), and IS-IS configuration on the Nokia 7750 SR running SR OS, including Segment Routing extensions (TLV 22/135/242 sub-TLVs).

Assessment

40 multiple-choice questions covering IS-IS fundamentals (PDU types, NET addressing, OSI CLNS), adjacencies and levels (L1/L2, DIS election, authentication), LSDB and SPF (flooding, route leaking, wide metrics), and IS-IS on Nokia SR OS (configuration, BFD, multi-topology, Segment Routing).

Time Limit

90 minutes

Passing Score

70%

Exam Fee

$125 (Nokia / Pearson VUE)

Nokia IS-IS Routing Protocol Exam Content Outline

25%

IS-IS Fundamentals

ISO 10589 origin, OSI CLNS, NSAP and NET addressing (area + 6-byte system ID + NSEL 0x00), AFI 49, the four PDU types (IIH, LSP, CSNP, PSNP), default hello = 10 s and hold = 30 s, and Integrated IS-IS for IP per RFC 1195.

25%

Adjacencies and Levels

Level 1 (intra-area) vs Level 2 (backbone), L1L2 routers, the ATT bit, DIS election (highest priority then highest SNPA, no BDIS), broadcast vs point-to-point IIHs, RFC 5303 three-way handshake, and IS-IS authentication via clear-text, HMAC-MD5, and HMAC-SHA key chains.

25%

LSDB and SPF

LSP flooding rules, sequence numbers, remaining lifetime, purges, CSNP/PSNP synchronization, LSP fragmentation, pseudonode LSPs, Dijkstra SPF, PRC, iSPF, route leaking with the RFC 2966 down bit, wide metrics in TLV 22/135, and the overload (OL) bit.

25%

IS-IS on Nokia SR OS

Configuring IS-IS on the 7750 SR (router isis context, area-id, level-capability, interface), metric-style wide/narrow/transition, default-information originate, summary-address, BFD-enable, LFA / TI-LFA, multi-topology IPv6 (MT 3), Segment Routing extensions (TLV 22 Adj-SID, TLV 135 Prefix-SID, TLV 242 SR-Capabilities/SRGB), and Flexible Algorithm.

How to Pass the Nokia IS-IS Routing Protocol Exam

What You Need to Know

  • Passing score: 70%
  • Assessment: 40 multiple-choice questions covering IS-IS fundamentals (PDU types, NET addressing, OSI CLNS), adjacencies and levels (L1/L2, DIS election, authentication), LSDB and SPF (flooding, route leaking, wide metrics), and IS-IS on Nokia SR OS (configuration, BFD, multi-topology, Segment Routing).
  • Time limit: 90 minutes
  • Exam fee: $125

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

Nokia IS-IS Routing Protocol Study Tips from Top Performers

1Memorize the four IS-IS PDU types and what each does: IIH discovers neighbors, LSP carries topology and prefixes, CSNP summarizes the LSDB (every 10 s on a LAN, once at startup on point-to-point), and PSNP acks and requests LSPs.
2Lock in NET parsing right-to-left: trailing 0x00 NSEL, then 6-byte system ID, then everything in front is the area address. Recognize AFI 49 as the OSI 'private' equivalent.
3Drill DIS election rules until they are reflexive: highest priority wins, MAC (SNPA) tiebreaker, IS-IS election is preemptive, and there is NO backup DIS - unlike OSPF's BDR.
4Master route leaking: L1 to L2 happens by default, but L2 to L1 requires an explicit policy on Nokia SR OS, and the RFC 2966 down (D) bit must be set on leaked prefixes to prevent loops.
5Memorize the major IS-IS TLVs: TLV 1 Area Addresses, TLV 6 IS Neighbors (LAN), TLV 22 Extended IS Reachability (wide metrics + sub-TLVs for TE/SR), TLV 135 Extended IPv4 Reachability, TLV 137 Dynamic Hostname, TLV 232/236 IPv6, TLV 240 P2P Three-Way, TLV 242 Router Capability (SR-Capabilities).
6Practice Nokia SR OS classic-CLI show commands until they are second nature: `show router isis adjacency`, `database`, `interface`, `routes`, `summary-address`, and `statistics` together cover most real-world troubleshooting.
7Run timed full-length 40-question mock exams and review every wrong answer; target 85% or higher in practice before booking the live 4A0-112 attempt.

Frequently Asked Questions

What is on the Nokia 4A0-112 IS-IS Routing Protocol exam?

Nokia 4A0-112 tests IS-IS theory and SR OS implementation: ISO 10589 fundamentals, OSI CLNS and NET addressing, the four PDU types (IIH, LSP, CSNP, PSNP), Level 1 and Level 2 areas with DIS election, point-to-point vs broadcast adjacency formation, LSP flooding and CSNP/PSNP database synchronization, Dijkstra SPF with PRC and iSPF, route leaking and the RFC 2966 down bit, wide metrics (RFC 5305), IPv6 single-topology and multi-topology IS-IS, authentication with HMAC-MD5 and HMAC-SHA, IS-IS configuration on the Nokia 7750 SR including BFD, summarization, and Segment Routing TLV extensions.

How long is the Nokia 4A0-112 exam and how many questions does it have?

The 4A0-112 IS-IS Routing Protocol exam contains 40 multiple-choice questions and gives candidates 90 minutes to complete it. The full Pearson VUE appointment is slightly longer because Nokia adds a brief computer-based-test tutorial before the timed exam begins.

What is the passing score for Nokia 4A0-112?

Nokia requires a 70% score to pass 4A0-112, which equates to roughly 28 of 40 questions correct. Treat that as a hard floor and aim higher in practice exams, since deep IS-IS topics like route leaking with the down bit, wide-metric TLVs (22, 135, 236), and Segment Routing sub-TLVs (TLV 242 SR-Capabilities, Prefix-SID, Adj-SID) drive most candidate failures.

How much does the Nokia 4A0-112 exam cost?

The 4A0-112 exam fee is $125 USD per attempt, paid to Pearson VUE at registration. Optional Nokia self-paced or instructor-led IS-IS Routing Protocol training is sold separately and is not required to sit the exam. Some Nokia partner organizations and university programs offer discounted vouchers.

How long is the Nokia SRC IS-IS credential valid?

Nokia SRC credentials, including 4A0-112, are valid for three years. To stay current, candidates must pass any current SRC exam (NRS I, NRS II, or another specialist exam such as 4A0-113 OSPF or 4A0-103 MPLS) within the three-year window or recertify by retaking 4A0-112.

Are there prerequisites for Nokia 4A0-112?

There are no formal prerequisites for 4A0-112, but Nokia strongly recommends NRS I (4A0-100) and prior hands-on IP routing experience before attempting it. Candidates should already be comfortable with IS-IS area design and OSPF concepts; the exam goes deeper than NRS I into IS-IS PDU internals and SR OS-specific configuration.

How does Nokia 4A0-112 compare with Cisco / Juniper IS-IS exams?

Nokia 4A0-112 is roughly comparable in scope to Cisco IS-IS coverage in CCIE Service Provider written and Juniper JNCIS-SP IS-IS sections. The protocol fundamentals (PDUs, levels, DIS election, RFC 1195/2966/5303/5305/5308/5310) are identical, but 4A0-112 emphasizes Nokia SR OS classic-CLI commands (`show router isis adjacency / database / interface / summary-address`) and Nokia-specific design patterns.