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Exam Information
Official specifications published by Juniper
Exam Format
Registration
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Skills this practice test covers
- Explain how the Routing Engine and the Packet Forwarding Engine split control and forwarding work.
- Change a candidate configuration and commit it safely with commit check and commit confirmed.
- Set up a new device from its factory default configuration with users, login classes and interfaces.
- Predict the active route from route preference and longest prefix match.
- Write routing policies and firewall filters from terms, match conditions and actions.
- Check interface statistics for errors, and recover a lost root password.
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JN0-105 exam content
7 domains · 43 topics · 111 of 360 questions are written for JN0-105
Networking Fundamentals16 questions
This domain checks the networking base that all Junos work rests on. Candidates explain collision and broadcast domains, Ethernet, MAC and IP addressing, longest match routing, CoS and the transport protocols.
Skills tested
- Tell collision domains from broadcast domains, and routers from switches.
- Subnet IPv4 networks and convert between decimal and binary.
- Read IPv6 addresses, including link-local and global unicast addresses.
- Explain how address resolution maps an IP address to a MAC address.
- Compare connection-oriented and connectionless transport protocols.
Questions by topic
- Function of routers and switches3
- IPv63
- Subnetting and supernetting2
- Layer 2 addressing, including address resolution3
- Decimal to binary conversion2
- Connection-oriented vs. connectionless protocols2
- CoS1
Junos OS Fundamentals15 questions
This domain explains how Junos OS is built. Candidates describe the split between the control plane and the forwarding plane, and how the device handles transit traffic and exception traffic.
Skills tested
- Describe the roles of the Routing Engine and the Packet Forwarding Engine.
- Explain how the forwarding table in the Packet Forwarding Engine is built from the routing table.
- Tell transit traffic from exception traffic, and name the engine that handles each.
Questions by topic
- Exception traffic4
- Routing vs. forwarding tables1
- Control and forwarding planes5
- Transit traffic processing3
- Routing engine and packet-forwarding engine2
User Interfaces13 questions
This domain covers the two ways to manage a device: the CLI and J-Web. Candidates move between operational and configuration mode, filter output, and work with the active and candidate configurations.
Skills tested
- Move around the CLI with command completion and context-sensitive help.
- Filter command output with pipe options such as match, except, find, count and last.
- Compare the candidate configuration with the active one, and roll back to an earlier version.
- Load configuration files with load merge, load replace or load override.
- Use J-Web for core configuration and monitoring tasks.
Questions by topic
- Viewing, comparing, and loading configuration files1
- Active vs. candidate configuration2
- CLI navigation5
- Filtering output3
- Reverting to previous configurations2
Configuration Basics20 questions
This domain is the first day with a new device. Candidates start from the factory-default state, add users and login classes, configure interfaces and system services, and protect the work with archival and a rescue configuration.
Skills tested
- Complete the initial setup of a device from its factory default configuration.
- Create user accounts with password or SSH key authentication and custom login classes.
- Configure interfaces and their logical units with the right families, such as inet and inet6.
- Write configuration groups once and apply them through group inheritance.
- Set up NTP, SNMP, system logging and automatic configuration archival.
Questions by topic
- Configuration groups5
- Login classes and user authentication methods3
- Viewing, comparing, and loading configuration files2
- Rescue configuration2
- User authentication methods2
- Factory-default state2
- Interface types and properties2
- Logging and tracing2
Operational Monitoring and Maintenance14 questions
This domain is the routine care of a running device. Candidates read show and monitor command output, check interface errors, use network tools, upgrade Junos OS and recover a lost root password.
Skills tested
- Use show and monitor commands to check the state of a device.
- Find interface problems such as CRC errors, drops and duplex mismatches.
- Test connectivity with the network diagnostic tools.
- Upgrade Junos OS, and shut a device down gracefully.
- Recover a lost root password.
Questions by topic
- Interface statistics and errors3
- Routing instances, Network tools1
- Network tools4
- Root password recovery3
- Monitor commands3
Routing Fundamentals16 questions
This domain is about how a Junos device decides where traffic goes. Candidates compare routing and forwarding tables, rank routes by preference, use routing instances and configure static routes.
Skills tested
- Explain the difference between the routing table and the forwarding table.
- Predict which route becomes active from its route preference.
- Describe routing instances, including the default routing instance, master.
- Configure static routes, including a default route and discard or reject routes.
- State when a dynamic routing protocol suits a network better than static routes.
Questions by topic
- Route preference3
- Static routing3
- Routing vs. forwarding tables1
- Routing instances3
- Routing tables2
- Routing instances, Network tools2
- Longest match routing2
Routing Policy and Firewall Filters17 questions
The last domain controls which routes are shared and which packets pass. Candidates build routing policies and firewall filters from terms, match conditions and actions, and predict how each one changes routes or packets.
Skills tested
- Explain the default import and export policies.
- Write a policy term with match conditions and actions such as accept, reject, next term or next policy.
- Build input and output firewall filters that accept, discard, count or log packets.
- Use unicast reverse-path forwarding to drop packets with spoofed source addresses.
Questions by topic
- Effect of policies on routes and routing tables3
- Filter structure, terms, match criteria, and actions3
- Routing policy flow3
- Filter match criteria and actions4
- Firewall filter concepts2
- Unicast reverse-path-forwarding (RPF)2
Requirements
- No formal prerequisites: anyone can book the exam.
- Recommended: a basic understanding of TCP/IP and of common network devices.
- Recommended: some practical time with Junos OS, on a device or in a virtual lab.
About the JN0-105 exam
JN0-105 tests the first layer of Junos knowledge: how Junos OS is built, how to configure and monitor a device, and how the device routes and filters traffic. It is the JNCIA-Junos exam for networking beginners, in the version based on Junos OS 21.2. The first domain reviews networking fundamentals, such as subnetting and Ethernet, before the Junos topics begin. No earlier certification is needed, and passing earns the Juniper Networks Certified Associate - Junos certification.
The PlanetCert practice test spreads its questions across all seven domains, and Configuration Basics is the largest group, from configuration groups to the rescue configuration. The explanations follow the Junos logic one step at a time. For example, they show why a route with a lower preference wins, or how a policy works through its terms in order. Study Mode suits the commit and rollback questions, where the order of the steps matters. Brainy AI Assistant answers follow-up questions, for example how the routing table differs from the forwarding table, or what commit confirmed protects against.
How to earn the certification
- Earns
- Juniper Networks Certified Associate - Junos (JNCIA-Junos)Associate
The certification is valid for three years.
- After
- JN0-351 Enterprise Routing and Switching, Specialist (JNCIS-ENT)
The specialist step for enterprise routing and switching.
- JN0-364 Service Provider Routing and Switching, Specialist (JNCIS-SP)
The specialist step for service provider routing and switching.
- JN0-336 Juniper Security Specialist (JNCIS-SEC)
The specialist step for security on Juniper devices.
- JN0-481 Data Center, Specialist (JNCIS-DC)
The specialist step for data center networks.
- JN0-351 Enterprise Routing and Switching, Specialist (JNCIS-ENT)
How to prepare for JN0-105
- 1
Confirm the version on the booking page
This practice test follows the JN0-105 objectives, based on Junos OS 21.2. JN0-106 is the newer version of the exam, so check which one is offered before planning study time.
- 2
Get a Junos device to practise on
Use a lab device or a virtual Junos device, and type every command by hand. Configuration Basics has the most questions in the practice test.
- 3
Commit, compare and roll back
Change the candidate configuration, run commit check, then try commit confirmed and a rollback. Repeat until the active and candidate configurations are easy to tell apart.
- 4
Trace a packet through the device
For one transit packet and one packet addressed to the device, say which engine handles it, which table it uses, and which filter or policy applies.
- 5
Finish on the full practice test
Once the lab work feels routine, run the JN0-105 practice test in Timed Mode. Ask Brainy AI Assistant about every missed route preference or filter question, then retry that domain in Study Mode.
Start a timed JN0-105run
Who JN0-105 is for
- Network engineers who are new to Juniper equipment.
- Support staff and network administrators who look after Junos devices.
- IT professionals who are moving to Juniper platforms from another vendor.
- Students on a networking path who want a vendor certification at associate level.
Typical job titles: Network engineer · Network administrator · Network support engineer · NOC technician · Junior network engineer
JN0-105 glossary
16 terms from the exam objectives and the vendor's official material, each defined in a sentence.
- Active configuration
- The configuration that the device is running now, which is the most recently committed one.
- Candidate configuration
- The copy of the configuration that is being edited. Nothing on the device changes until it is committed.
- commit confirmed
- A commit that rolls back on its own unless a second commit confirms it in time, which protects against losing remote access.
- Configuration groups
- Reusable blocks of configuration that other parts of the configuration inherit, so that a setting is written only once.
- Exception traffic
- Packets that the Packet Forwarding Engine cannot simply forward, such as traffic addressed to the device itself, so they go to the Routing Engine.
- inet.0 (IPv4 unicast)
- The main Junos routing table for IPv4 unicast routes.
- J-Web
- The browser-based interface for configuring and monitoring a Junos device.
- Logical interfaces (unit)
- The units configured under a physical interface, where Junos places addresses and protocol families.
- Login classes
- Sets of permissions that decide which commands a user account may run.
- Longest prefix match
- The rule that, when several routes match a destination, the route with the most specific prefix decides where the packet goes.
- Packet Forwarding Engine (PFE)
- The forwarding plane of a Junos device. It moves transit traffic using the forwarding table that the Routing Engine builds.
- Rescue configuration
- A saved, known-good configuration that can be loaded to bring a device back into a working state quickly.
- Route preference
- The value Junos uses to rank routes from different sources. The lowest value wins, so a direct route beats a BGP route.
- Routing Engine (RE)
- The control plane of a Junos device. It runs the routing protocols, the CLI and the management functions.
- Routing Instances
- Separate sets of routing tables and interfaces on one device. The default routing instance is called master.
- Unicast reverse-path-forwarding (RPF)
- A check that drops a packet when the best route back to its source does not use the interface the packet arrived on.