- Identity Check: Which NRS I This Is
- The Exam at a Glance
- The Six Modules in One Page
- Numbers and Mechanics to Memorize
- SR OS and MD-CLI Quick Reference
- Routing and Services: The Concepts That Link Together
- Easy-to-Confuse Pairs
- Mapping the Modules to a Revision Plan
- What This Cheat Sheet Deliberately Does Not Claim
- FAQ
- NRS I is Nokia's Network Routing Specialist I, earned through the single mandatory 4A0-100 exam.
- The exam is 40 multiple-choice questions in 90 minutes; the 110-minute appointment includes a 20-minute survey.
- The published exam fee is USD 125; training prices are separate and should not be confused with it.
- Six modules with 28 subtopics form the preparation outline, but they are not weighted exam domains.
Identity Check: Which NRS I This Is
The acronym "NRS I" is shared by several unrelated credentials. This page covers only Nokia Network Routing Specialist I, the entry-level routing and services certification from Nokia. If you are looking for background on the name itself, see What Does NRS I Stand For? or What Is NRS I Certification?. Everything below is specific to the Nokia credential and its single required exam.
The certification is built on foundational networking knowledge applied to Nokia's service router platform. It is not a lab exam and it is not a composite of several tests. One exam, 4A0-100, earns it. Do not substitute requirements from NRS II or the Service Routing Architect (SRA) track; those carry their own lab and composite requirements, which do not apply here.
The Exam at a Glance
| Item | Fact |
|---|---|
| Certification | Nokia Network Routing Specialist I (NRS I) |
| Governing body | Nokia |
| Required exam | 4A0-100 IP Networks and Services Fundamentals |
| Format | Multiple choice |
| Questions | 40 |
| Exam duration | 90 minutes |
| Appointment length | 110 minutes, including a 20-minute introductory survey |
| Published exam fee | USD 125 |
| Mandatory exam prerequisite | None listed |
| Pass threshold, scored/unscored split, pass rate | Not established in the sources reviewed |
For the money side, including how exam fees differ from course pricing, read the NRS I certification cost breakdown. For eligibility details, see NRS I requirements.
The Six Modules in One Page
Nokia designates six modules, containing 28 subtopics in total, as the candidate preparation outline. The exam page directs candidates to the course objectives and modules. These are not weighted exam domains and should not be treated as an exhaustive blueprint, so do not budget study time by assuming equal or fixed percentages. A fuller walkthrough lives in the NRS I exam domains guide.
Domain 1: Introduction to Networking and Services
The conceptual foundation for everything that follows.
- Protocol-layer models (layered TCP/IP)
- Encapsulating and decapsulating traffic as it moves through layers
- Separating control from forwarding (control plane versus data plane)
Domain 2: Service Router Components and Command Line Interface
Where the Nokia-specific material concentrates.
- Service-router product range and where each product fits in a network
- 7750 SR hardware
- Router boot sequence
- Operating and configuring SR OS from the CLI
Domain 3: Ethernet
Layer 2 behavior and structure.
- Access to shared media
- Hub versus switch behavior
- Link-layer addressing
- VLAN segmentation
- Redundant Ethernet
- Frame structure
Domain 4: The Internet Layer
IPv4 and how packets are forwarded.
- IPv4 addressing
- Subnetting and summarizing routes
- 7750 SR layer 3 interfaces
- Forwarding decisions
- Packet-header fields
- Residential and small-business connectivity
Domain 5: IP Routing Protocol Basics
How routes get into the table.
- Static route configuration
- OSPF fundamentals
- BGP introduction
- Internet building blocks
Domain 6: Services Overview
The payoff: carrying customer traffic across a provider network.
- VPN concepts
- MPLS tunnel transport
- Distributing labels with LDP
- Elements of a VPN service
- VPWS, VPLS, and VPRN configuration
Numbers and Mechanics to Memorize
Most of NRS I is conceptual, but a handful of hard facts are worth committing to memory because they are easy to mix up on exam day.
- Exam code: 4A0-100, titled IP Networks and Services Fundamentals.
- Counts: 40 questions, 90 minutes, 6 modules, 28 subtopics.
- Money: USD 125 exam fee. Course or training prices are separate and are not the exam fee.
- Scheduling quirk: The appointment runs 110 minutes because of a 20-minute introductory survey.
- Transition dates: Revised exam announced for 2027-03-09, with unavailability 2027-02-09 through 2027-03-08. This cheat sheet reflects the October 2026 scope, so recheck Nokia's exam page before booking anywhere near that window. Scheduling specifics are covered in the NRS I exam dates guide.
SR OS and MD-CLI Quick Reference
The current course uses the model-driven CLI (MD-CLI), so expect configuration concepts framed around it. The learning objectives call for candidates to place Nokia router products in networks, use the 7750 SR CLI, and configure service components. Questions in this area test whether you understand how the router is organized and operated, not just whether you recognize command keywords.
What to know cold
- Product range: Know that the service-router family spans multiple products and be able to reason about where each kind of router belongs in a network.
- 7750 SR hardware: Understand the main hardware building blocks and the division of work between control and forwarding functions, which ties back to Module 1.
- Boot sequence: Be able to describe the order in which the router comes up, in general terms, and why it matters for troubleshooting.
- Operating and configuring SR OS: Know the difference between navigating and viewing state versus changing configuration, and how a candidate-style configuration workflow differs from a classic immediate-apply CLI.
Key Takeaway
Do not memorize command syntax in isolation. Learn what each configuration block accomplishes, such as an interface, a routing protocol instance, or a service, so you can recognize the right answer even when the wording differs from the course material.
Routing and Services: The Concepts That Link Together
The six modules are not independent silos. The exam rewards candidates who see the chain from frames to services. Here is the dependency in compressed form:
- Frames carry packets. Ethernet frame structure, link-layer addressing, and VLANs determine how traffic moves within a segment.
- Packets are forwarded by IP. IPv4 addressing, subnetting, packet-header fields, and forwarding decisions determine how traffic moves between segments.
- Routes are learned statically or dynamically. Static configuration, OSPF, and BGP fill the forwarding decision with information.
- MPLS provides the transport tunnels. LDP distributes the labels that make those tunnels work.
- Services ride the tunnels. VPWS, VPLS, and VPRN present different customer-facing service types over the shared transport.
Static versus dynamic routing
Know when each makes sense. Static routes are simple, predictable, and require manual maintenance. Dynamic protocols adapt to topology changes but add protocol complexity. OSPF is the interior routing protocol covered at the fundamentals level; BGP is introduced as the protocol connecting independently operated networks, which is why "Internet building blocks" sits alongside it in Module 5.
VPN service types
| Service | Think of it as | Key idea to retain |
|---|---|---|
| VPWS | A point-to-point pseudowire | Emulates a dedicated link between two sites |
| VPLS | A virtual LAN across the provider network | Layer 2 multipoint connectivity |
| VPRN | A virtual routed network | Layer 3 connectivity with provider-routed customer traffic |
Pair that table with the transport story: MPLS tunnels carry the traffic, and LDP is the mechanism that distributes labels for them. Expect questions that ask you to distinguish the service from the transport underneath it.
Easy-to-Confuse Pairs
- Hub versus switch: A hub repeats traffic onto shared media; a switch makes forwarding decisions based on link-layer addresses.
- Control versus forwarding: Control builds the information; forwarding uses it to move packets.
- Encapsulation versus decapsulation: Headers are added moving down the layers and removed moving up.
- Layer 2 versus Layer 3 service: VPLS behaves like a LAN; VPRN involves routing the customer's IP traffic.
- Exam time versus appointment time: 90 minutes versus 110 minutes.
- Exam fee versus training price: USD 125 is the exam; training is priced separately.
- NRS I versus NRS II or SRA: Different certifications with different requirements. Nothing about their lab or composite structure applies here.
Mapping the Modules to a Revision Plan
Because the modules build on one another, revise in dependency order rather than in whatever order feels comfortable. This is one possible six-week arrangement; compress or stretch it to match your background. For a fuller approach, see the NRS I study guide.
Foundations and Ethernet
- Layered models, encapsulation, control versus forwarding
- Frame structure, VLANs, hub versus switch, redundant Ethernet
The Internet Layer
- IPv4 addressing, subnetting, summarization drills
- Packet-header fields and forwarding decisions
SR hardware and CLI
- Product range, 7750 SR hardware, boot sequence
- MD-CLI navigation and configuration, layer 3 interfaces
Routing protocol basics
- Static routes, OSPF fundamentals, BGP introduction
Services overview
- VPN concepts, MPLS transport, LDP label distribution
- VPWS, VPLS, VPRN elements and configuration
Integration and rehearsal
- Timed sets of 40 questions in 90 minutes
- Re-read this cheat sheet and recheck Nokia's exam page for changes
The ordering is deliberate. Subnetting and routing make far more sense after you understand Ethernet and IP forwarding, and VPN services make far more sense after you understand routing and MPLS transport. When you are ready for timed rehearsal, the NRS I practice tests provide original supplemental questions. They are study aids, not actual exam content, and they carry no endorsement from Nokia or any guarantee of results.
What This Cheat Sheet Deliberately Does Not Claim
A trustworthy one-pager is as clear about its limits as its facts. A few things you should not expect from this page:
- No module weightings. The six modules are an issuer-designated preparation outline, not a weighted blueprint.
- No passing score or pass rate. None is established in the sources reviewed.
- No claim of exhaustive coverage. The outline is a guide to preparation, and exam questions may touch material in more or less detail than the course.
- No salary figures. For career context, see the NRS I salary guide, whether NRS I is worth it, and NRS I jobs.
This content reflects Nokia's published information as reviewed on October 11, 2026, from the Nokia exam, certification, and course pages. Always confirm current details directly with Nokia before registering. To judge how demanding the material is for your background, read how hard the NRS I exam is, then test yourself with the main practice test site.
FAQ
One. NRS I requires the single mandatory 4A0-100 IP Networks and Services Fundamentals exam. Do not apply NRS II or SRA requirements to it.
It has 40 multiple-choice questions and a 90-minute examination time. The appointment is 110 minutes because it includes a 20-minute introductory survey, which is not part of the exam duration.
The published exam fee is USD 125. Training and course prices are separate, so budget for them independently if you plan to take the course.
No. The six modules and their 28 subtopics are Nokia's designated preparation outline, not a weighted examination blueprint. Study all of them rather than guessing at percentages.
Nokia announces a revised exam on 2027-03-09, with unavailability from 2027-02-09 through 2027-03-08. This cheat sheet reflects the October 2026 scope, so recheck Nokia's exam page before scheduling near that transition.