4A0-C03 Exam Preparation Material | Nokia NRS II Composite Exam: IS-IS version

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Prepare for the 4A0-C03 Nokia NRS II Composite : IS-IS version exam with CertQueen's independently developed study resources. Review important concepts, practice scenario-based questions, and use clear explanations to identify areas that require further study.

Question#1

In a large VPLS network with redundant core links, what specific mechanism does Nokia SR OS use to rapidly update the MAC Forwarding Database (FDB) when a topology change occurs, preventing traffic blackholing?

A. BGP Route Refresh messages

B. STP Topology Change Notifications (TCN)

C. OSPF Network LSAs

D. LDP MAC Flush messages

Explanation:
When an access link or node fails in a VPLS environment (especially in redundant setups like active/standby Spoke-SDPs or MC-LAG), the PE router sends an LDP MAC Flush message to the remote PEs. This instructs them to instantly flush the old MAC addresses associated with that path, forcing a quick re-learning of the new active path.

Question#2

Which BGP Extended Community is strictly utilized by MP-BGP to instruct a receiving PE router on which VPRN (VRF) an incoming VPN-IPv4 route should be imported into?

A. Route Distinguisher (RD)

B. Site of Origin (SoO)

C. Route Target (RT)

D. Originator ID

Explanation:
The Route Target (RT) is a BGP extended community that acts as the "color" or "tag" for a route. The receiving PE checks its import policies to see if any local VPRNs are configured to accept (import) that specific RT.

Question#3

When troubleshooting a routing issue, you issue the command show router route-table 10.1.1.1 . The output indicates the next-hop is a tunnel, but the traffic is failing. What command would you use to verify the specific MPLS labels being pushed for this destination?

A. show router ldp bindings active

B. show router mpls forwarding-table

C. show router fib 10.1.1.1

D. show router tunnel-table

Explanation:
In SR OS, the show router tunnel-table is the ultimate command to verify how BGP next-hops (or IGP next-hops) are resolved to specific transport tunnels (RSVP, LDP) and what the outbound transport label (outer label) will be.

Question#4

You want to ensure that an RSVP-TE LSP strictly avoids a specific high-latency physical link during its CSPF path calculation. Which MPLS Traffic Engineering feature is best suited for this?

A. Multi-Exit Discriminator (MED)

B. Targeted LDP (tLDP)

C. Administrative Groups (Colors)

D. Fast Reroute (FRR)

Explanation:
Administrative Groups (also known as Link Colors) allow you to assign attributes to physical links (e.g., "high-latency", "encrypted"). You can then configure the CSPF path of an LSP to explicitly include or exclude links matching those specific groups.

Question#5

To prevent a transit AS from being used for traffic destined to your AS, you decide to use BGP AS-Path prepending to make the route look artificially longer. Where should this policy be applied?

A. As an import policy on your iBGP sessions.

B. As an export policy on your eBGP sessions.

C. As an export policy on your iBGP sessions.

D. As an import policy on your eBGP sessions.

Explanation:
AS-Path prepending is used to influence inbound traffic (how other autonomous systems reach you). To do this, you prepend your own AS number multiple times to the routes you advertise outwards. Therefore, it is applied as an export policy to your eBGP peers.

Exam Code: 4A0-C03
Q & A: 70 Q&As Updated: Nov 02,2026

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Identify Knowledge Gaps

Use your results and the provided explanations to find weaker areas and focus your study more effectively.

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Exam Code: 4A0-C03
Q & A: 70 Q&As
Updated: Nov 02,2026