Nokia IP Networks and Services Fundamentals 4A0-100 Exam Questions

Answer : D

OSPF (Open Shortest Path First) is a Link-State protocol that uses:

Cost (based on bandwidth) as its metric.

Dijkstra's algorithm to compute shortest path trees.

Supports hierarchical routing with areas (e.g., Area 0 as backbone).

Routers exchange LSAs, not full routing tables.

Option D is FALSE -- OSPF does not use hop-count. That's a RIP (Distance Vector) feature.

Nokia IP Routing Guide -- Section: ''OSPF Operation and Area Design''

RFC 2328 -- OSPFv2 Protocol Specification

Answer : C

A layered protocol stack is designed to simplify network communication by separating functionalities into distinct layers. Each layer has a defined role and communicates with the layers directly above and below it. The main benefits of this model include:

Simplified design and implementation: Developers can focus on one layer without needing to understand the entire system.

Flexibility: New protocols can be developed and inserted at specific layers without redesigning the whole stack.

Interoperability: Standard interfaces allow different systems and vendors to work together.

Isolation of functions: Errors and updates can be managed within one layer without impacting others.

However, reducing protocol overhead is not a primary goal of this model. In fact, the encapsulation and interaction between layers can sometimes introduce extra overhead. This overhead is a trade-off accepted to gain the other benefits listed above.

Answer : D

VPWS (Virtual Private Wire Service) on Nokia 7750 SR:

Emulates a Layer 2 point-to-point connection.

Does not require MAC learning, unlike VPLS.

Uses MPLS encapsulation, not IP datagrams for transport.

Option D is FALSE -- VPWS uses MPLS labels, not IP encapsulation.

Nokia 7750 SR Service Router Guide -- VPWS Overview

Nokia SRA Study Guide -- Chapter: Layer 2 Services

Answer : C

The Internet Assigned Numbers Authority (IANA) is responsible for managing the global IP address pool, along with:

Allocating blocks of IP addresses to Regional Internet Registries (RIRs) such as ARIN (North America), RIPE NCC (Europe), APNIC (Asia-Pacific), etc.

Managing autonomous system numbers (ASNs).

Overseeing DNS root zones and protocol parameters.

IANA does not assign IPs directly to enterprises or individuals --- those tasks are delegated to RIRs and ISPs.

Option A & B: Enterprises and residential allocations are handled by ISPs or RIRs.

Option D: North American IPs are managed by ARIN, not IANA.

Option C is correct -- IANA manages the global IP address allocation hierarchy.

IANA official site: https://www.iana.org

Nokia IP Fundamentals -- IP Address Management and Allocation Hierarchy

Answer : C

VPLS (Virtual Private LAN Service) is a Layer 2 VPN service that emulates a bridged Ethernet LAN across an MPLS/IP network.

Learns MAC addresses dynamically from:

SAPs (Service Access Points)

SDPs (Service Distribution Points)

Maintains a Forwarding Database (FDB) per VPLS instance.

For unknown MAC destinations, a VPLS floods the frame to all other sites -- just like a regular Ethernet switch.

Option C is FALSE -- VPLS does NOT discard unknown MACs; it floods them.

Nokia VPLS Services Guide -- Learning and Forwarding

Nokia SRA Study Guide -- VPLS Operation

Answer : C

A VPRN (Virtual Private Routed Network) provides a Layer 3 VPN service over a service provider's network.

Each customer site connects to a PE router.

Sites are connected via a routed network using separate routing instances.

Customer routers see routed connectivity, as if connected to their own private WAN.

Option C is correct -- VPRN provides routed connectivity between sites.

Nokia Service Routing Guide -- Chapter: VPRN

Nokia SRA Guide -- Service Types and Operation

Answer : B

The system interface in Nokia SR OS is a loopback-style logical interface that represents the router itself. It is used for:

Router ID assignment (if not manually set)

Source IP for control-plane protocols (OSPF, BGP)

Reachability testing

Important properties:

It is type loopback

It exists by default

If router ID is unset, it uses the system IP address

But the IP address on the system interface does not need to be /32

It can have other prefix lengths, especially in service provider scenarios.

Thus, Option B is FALSE.

Nokia SRA Study Guide -- Chapter: 'System Interface and Loopbacks'

Nokia SR OS Fundamentals Guide -- System IP Configuration Section