NRS I Exam Domains 2026: Complete Guide to All 6 Content Areas

How to Read the Six-Module Outline

Many certification guides present exam content as a tidy table of percentages. Nokia does not do that for the Network Routing Specialist I (NRS I) credential, and any article that hands you precise domain weights is guessing. What Nokia publishes is a set of six issuer-designated candidate exam-topic modules, with 28 subtopics beneath them. The exam page directs candidates to the course objectives and modules, and the outline is explicitly a preparation guide rather than a weighted examination blueprint or an exhaustive list of what could appear.

That distinction shapes how you should study. Without published weights, you cannot safely skip a module because it "probably" carries fewer questions. With only 40 questions on the exam, a single weak module can cost you a meaningful share of your result, so the sensible approach is breadth first, then depth where your own practice results show gaps.

This guide walks through all six modules in the order Nokia presents them, explains what each subtopic actually demands of you, and flags where candidates from different backgrounds tend to need extra attention. For a broader view of the whole preparation process, pair it with the NRS I study guide.

The 4A0-100 Exam Format and Registration Mechanics

NRS I is earned through a single mandatory exam: 4A0-100 IP Networks and Services Fundamentals. It is a multiple-choice exam with 40 questions and a 90-minute time limit, which works out to a little over two minutes per question. That is a comfortable pace if you know the material, but it is not so generous that you can afford to puzzle over every item.

A few mechanics trip people up:

• The appointment is longer than the exam. The scheduled appointment is 110 minutes because it includes a 20-minute introductory survey. That survey is not part of your examination time. Your clock for the questions is 90 minutes.
• No mandatory exam prerequisite is listed. You do not need to pass another Nokia exam first. For details on eligibility, see the NRS I requirements guide.
• The exam fee is USD 125. Training is priced separately, and course purchase prices are training facts, not exam fees. The NRS I certification cost breakdown separates the two cleanly.
• Scoring details are not established here. There is no confirmed current pass threshold, scored/unscored split, or pass rate in the sources reviewed, so be wary of anyone quoting a precise cut score. The passing score article covers what is and is not known.

One more point of scope discipline: NRS I requires 4A0-100 and nothing else. Do not assume the lab or composite-style requirements associated with higher Nokia credentials such as NRS II or SRA apply here. They do not.

Domain 1: Introduction to Networking and Services

Protocol-layer models

You need to explain layered TCP/IP clearly and place protocols and devices at the correct layer. Expect questions that describe a behavior and ask which layer is responsible, or which device operates where. Memorizing a layer list is not enough; you should be able to reason about why a given function belongs at a given layer.

Encapsulation and decapsulation

Know what happens to data as it moves down the stack on the sender and back up on the receiver: headers are added, then removed in reverse order. A common stumbling block is confusing what each layer adds. Practice describing the journey of a single packet from application data to a frame on the wire.

Separating control from forwarding

This is a conceptual idea that pays off throughout the exam. The control plane decides where traffic should go (building routing information), while the forwarding plane moves packets according to those decisions. When you reach OSPF, BGP, and MPLS later, this separation is what makes them make sense.

Domain 2: Service Router Components and Command Line Interface

Product range and 7750 SR hardware

One learning objective is placing Nokia router products in networks. That means understanding where the service-router family fits and what the 7750 SR hardware is made of at a functional level. Focus on the role each component plays rather than trying to memorize part details in isolation.

Router boot sequence

Be ready to describe the order in which a service router comes up and how it loads its software and configuration. Questions here reward understanding of sequence: what must happen before what.

Operating and configuring SR OS

The current course uses the model-driven CLI (MD-CLI), so make sure the material you study reflects it rather than only older syntax. You should be comfortable with how the CLI is structured, how configuration is entered and committed, and how to inspect state. Hands-on time, even in a lab or demo environment, helps enormously here, because CLI structure is much easier to recall after you have typed it.

Domain 3: Ethernet

Shared media and hub versus switch behavior

Understand how devices contend for a shared medium and why switching changed that picture. You should be able to contrast how a hub repeats traffic with how a switch learns addresses and forwards selectively, including what happens to unknown destinations.

Link-layer addressing and frame structure

Know what a MAC address is, how it is used, and what fields make up an Ethernet frame. Questions may present a frame description and ask what a particular field does, or ask how a switch uses addressing to make a forwarding decision.

VLAN segmentation and redundant Ethernet

VLANs segment a network logically, and tagging is how that separation is carried across links. Redundant Ethernet covers the idea of providing alternate paths while avoiding loops. Be clear on the problem redundancy solves and the problem it can create if unmanaged.

Domain 4: The Internet Layer

IPv4 addressing, subnetting, and route summarization

You must be able to work with IPv4 addresses and masks without a calculator: identify network and host portions, determine subnet boundaries, and recognize when a set of routes can be summarized into one. Practice this until it is fast. Under time pressure, slow subnetting is the most common way candidates lose minutes.

Layer 3 interfaces on the 7750 SR

This ties the addressing concepts back to the platform from Domain 2. Know how an IP interface is conceptually defined on the service router and how it relates to the underlying port.

Forwarding decisions and packet-header fields

Understand how a router looks up a destination and picks a next hop, including what happens when multiple routes could match. Know the purpose of key IPv4 header fields, such as those governing packet lifetime and fragmentation, and be able to reason about what a router does with them.

Residential and small-business connectivity

This subtopic frames how everyday customer connectivity relies on these Internet-layer fundamentals. Expect it to be applied, scenario-style material rather than deep protocol detail.

Domain 5: IP Routing Protocol Basics

Static route configuration

Know when static routes are appropriate, what information a static route needs, and the trade-offs against dynamic routing: simplicity and predictability versus manual effort and lack of automatic adaptation.

OSPF fundamentals

At this level, the emphasis is on understanding what OSPF is for and how it works conceptually: routers discover neighbors, exchange information about the network, and each builds a consistent view from which it computes best paths. Focus on the big ideas rather than exhaustive protocol internals.

BGP introduction

BGP appears as an introduction. You should understand its role as the protocol that exchanges routing information between independently administered networks, and how that differs in purpose from an interior protocol like OSPF. A clean way to hold the distinction: OSPF organizes routing within a network, while BGP connects networks to each other.

Internet building blocks

This subtopic places the protocols in the larger picture of how the Internet is assembled from many interconnected networks. It rewards candidates who can explain why both interior and exterior routing are needed.

Domain 6: Services Overview

VPN concepts and MPLS tunnel transport

Be able to explain what a VPN is and why operators use MPLS tunnels to carry customer traffic across a shared core. The key idea is that customer traffic rides inside transport tunnels, keeping customers separated while sharing infrastructure.

Distributing labels with LDP

Understand at a conceptual level how labels are distributed so that routers know how to forward labeled traffic. You do not need to treat this as an advanced MPLS deep dive; you need to know what LDP does and why it is needed.

Elements of a VPN service and VPWS, VPLS, VPRN

Learn the building blocks that make up a service and be able to tell the three service types apart. A reliable memory aid is to anchor each on what it emulates: VPWS provides a point-to-point connection, VPLS emulates a multipoint Layer 2 network, and VPRN delivers a routed Layer 3 VPN. Questions commonly give a customer requirement and ask which service fits.

Sequencing the Six Modules Across Your Prep

Because the modules build on each other, order matters more than any generic study technique. The sequence below follows dependencies: concepts first, platform next, Layer 2 and Layer 3 foundations after that, then routing, and services last because they draw on everything else.

Adjust the pace to your background. A candidate who already works with IP networks may compress Weeks 1 and 2, while someone new to networking should expand them. For how demanding the material tends to feel, see how hard the NRS I exam is, and for a condensed final review, the NRS I cheat sheet.

Where This Knowledge Gets Used

The six modules map to the kind of work done by people who operate and support IP service networks built on Nokia platforms. Telecommunications and service-provider environments are the natural home for this material, along with the vendors, integrators, and support organizations that work alongside them. Roles that touch service-router operations, network support, and service delivery are where an understanding of Ethernet, IP, OSPF/BGP, and MPLS-based VPN services comes up in daily work.

Be realistic about what a fundamentals-level credential signals: it demonstrates grounding in the concepts and the platform, not senior design experience. If you are weighing the career angle, the NRS I jobs overview and the worth-it analysis take that question further, and the salary guide addresses earnings.

Watch the 2027 Exam Revision

Practical advice: if you are ready well before February 2027, schedule comfortably ahead of the unavailability period rather than squeezing in at the last moment. If your timeline slips toward the transition, confirm which version of the exam you would be sitting and whether the module list has changed.

Frequently Asked Questions

Mastering the six modules is the surest way to be ready for 4A0-100. For a structured plan covering the whole journey, read the NRS I study guide, and use original timed practice at NRS I Exam Prep to find out which module needs your attention next. Practice material here is independent supplemental study content, not issuer-endorsed, not actual exam questions, and not a guarantee of results.