JNCIA EXAM QUESTIONS AND
ANSWERS (VERIFIED AND UPDATED)
The Control Plane runs on which Engine? The Forwarding Plane? - ANS Control Plane runs on
the Routing Engine. Forwarding Plane runs on the Packet Forwarding Engine.
Because software processes are compartmentalized, that means? (2 things) - ANS Each runs
in own protected memory space; new features can be added with less likelihood of breaking
current functionality.
In Juniper architecture, what is the primary function of the control plane? - ANS maintain
routing intelligence, control and monitor chassis, manage the PFE.
In Juniper architecture, what is the primary function of the forwarding plane? - ANS Forward
packets and implement advanced services.
How is transit traffic processed? - ANS For platforms running JunOS, forwarded through the
PFE based on forwarding table installed on the PFE.
How is exception traffic processed? - ANS processed locally either by the Routing Engine or
by the Packet Forwarding Engine depending on the type of traffic.
Which Juniper platforms run JunOS? - ANS These series: M, T, J, MX, EX, SRX
What does GRES stand for? - ANS Graceful Routing Engine Switchover.
@2026/2027 ALLRIGHTS RESERVED.
,What does NSR stand for? - ANS Nonstop Active Routing.
What does ISSU stand for? - ANS Unified in-service softwar upgrades.
Name 3 High Availability features. - ANS GRES - Graceful Routing Engine Switchover; NSR -
Nonstop Active Routing; ISSU - Unified in-service software upgrades
Define Exception traffic. Give examples. - ANS Traffic destined to the Juniper device itself.
Example: routing protocol updates, telnet sessions, traceroutes, replies to sourced traffic, traffic
requiring icmp replies.
M series - Multiservice Routers. How much throughput? Give example of deployment? -
ANS Throughput: up to 320 Gbps of aggregate half-duplex throughput. Deploy in high-end
enterprise, and service provider environments.
T series - Core routers. What is the throughput? Give example of deployment. -
ANS Throughput: up to 25.6 Tbps. Example deployment: service provider core.
J series - Services routers. What is the throughput? Give example of deployment. -
ANS Throughput: up to 2 Gbps. Example deployment: branch and remote locations.
MX series - Ethernet Services Router. What is the throughput? Give example of deployment. -
ANS Throughput: up to 960 Gbps of aggregate half-duplex throughput. Example deployment:
dense dedicated access aggregation & provider edges services.
EX series - Ethernet switches. What is the throughput? Give example of deployment. -
ANS Throughput: 6.2 Tbps full duplex. Example deployment: low to high density enterprise &
data center environments.
SRX series - Services Gateways. What is the throughput? Give example of deployment. -
ANS Throughput: up to 120 Gbps of full duplex. Example deployment: to meet
@2026/2027 ALLRIGHTS RESERVED.
, network/security requirements for consolidated data centers, managed services deployments,
aggregation of security services.
Which modes exist in JunOS? - ANS Operational, Configuration, FreeBSD shell.
JunOS Operational mode is used to do what? - ANS Monitor & Troubleshoot: the software,
network connectivity, and hardware.
The JunOS Configuration mode is used to do what? - ANS Configure: interfaces protocols,
user access, and system hardware.
What is the spacebar used for? - ANS Will complete actual commands
What is the tab used for? - ANS Will complete actual commands and variables such as
firewall filter name
What command is quickest to return to the uppermost level of the configuration hierarchy? -
ANS top
What is the difference between the Active and Candidate configurations? - ANS Difference is
whether the config has been committed and in use. Active = comitted and in use. Candidate =
doesn't become the Active config until commit command performed.
What is the command to display the difference between the candidate and active
configurations? - ANS show | compare
What are the three 'help' command options? - ANS help topic <topic> ; help reference
<config-statement> ; help apropos <keyword>
Key combo to: move left 1 character? - ANS Control B
@2026/2027 ALLRIGHTS RESERVED.
ANSWERS (VERIFIED AND UPDATED)
The Control Plane runs on which Engine? The Forwarding Plane? - ANS Control Plane runs on
the Routing Engine. Forwarding Plane runs on the Packet Forwarding Engine.
Because software processes are compartmentalized, that means? (2 things) - ANS Each runs
in own protected memory space; new features can be added with less likelihood of breaking
current functionality.
In Juniper architecture, what is the primary function of the control plane? - ANS maintain
routing intelligence, control and monitor chassis, manage the PFE.
In Juniper architecture, what is the primary function of the forwarding plane? - ANS Forward
packets and implement advanced services.
How is transit traffic processed? - ANS For platforms running JunOS, forwarded through the
PFE based on forwarding table installed on the PFE.
How is exception traffic processed? - ANS processed locally either by the Routing Engine or
by the Packet Forwarding Engine depending on the type of traffic.
Which Juniper platforms run JunOS? - ANS These series: M, T, J, MX, EX, SRX
What does GRES stand for? - ANS Graceful Routing Engine Switchover.
@2026/2027 ALLRIGHTS RESERVED.
,What does NSR stand for? - ANS Nonstop Active Routing.
What does ISSU stand for? - ANS Unified in-service softwar upgrades.
Name 3 High Availability features. - ANS GRES - Graceful Routing Engine Switchover; NSR -
Nonstop Active Routing; ISSU - Unified in-service software upgrades
Define Exception traffic. Give examples. - ANS Traffic destined to the Juniper device itself.
Example: routing protocol updates, telnet sessions, traceroutes, replies to sourced traffic, traffic
requiring icmp replies.
M series - Multiservice Routers. How much throughput? Give example of deployment? -
ANS Throughput: up to 320 Gbps of aggregate half-duplex throughput. Deploy in high-end
enterprise, and service provider environments.
T series - Core routers. What is the throughput? Give example of deployment. -
ANS Throughput: up to 25.6 Tbps. Example deployment: service provider core.
J series - Services routers. What is the throughput? Give example of deployment. -
ANS Throughput: up to 2 Gbps. Example deployment: branch and remote locations.
MX series - Ethernet Services Router. What is the throughput? Give example of deployment. -
ANS Throughput: up to 960 Gbps of aggregate half-duplex throughput. Example deployment:
dense dedicated access aggregation & provider edges services.
EX series - Ethernet switches. What is the throughput? Give example of deployment. -
ANS Throughput: 6.2 Tbps full duplex. Example deployment: low to high density enterprise &
data center environments.
SRX series - Services Gateways. What is the throughput? Give example of deployment. -
ANS Throughput: up to 120 Gbps of full duplex. Example deployment: to meet
@2026/2027 ALLRIGHTS RESERVED.
, network/security requirements for consolidated data centers, managed services deployments,
aggregation of security services.
Which modes exist in JunOS? - ANS Operational, Configuration, FreeBSD shell.
JunOS Operational mode is used to do what? - ANS Monitor & Troubleshoot: the software,
network connectivity, and hardware.
The JunOS Configuration mode is used to do what? - ANS Configure: interfaces protocols,
user access, and system hardware.
What is the spacebar used for? - ANS Will complete actual commands
What is the tab used for? - ANS Will complete actual commands and variables such as
firewall filter name
What command is quickest to return to the uppermost level of the configuration hierarchy? -
ANS top
What is the difference between the Active and Candidate configurations? - ANS Difference is
whether the config has been committed and in use. Active = comitted and in use. Candidate =
doesn't become the Active config until commit command performed.
What is the command to display the difference between the candidate and active
configurations? - ANS show | compare
What are the three 'help' command options? - ANS help topic <topic> ; help reference
<config-statement> ; help apropos <keyword>
Key combo to: move left 1 character? - ANS Control B
@2026/2027 ALLRIGHTS RESERVED.
