JN0-106 Junos, Associate (JNCIA-Junos) Practice Questions
Prepare for JN0-106 with more than an answer.
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- v1Junos, Associate (JNCIA-Junos) 150 questions Current
- JN0-103Legacy Junos, Associate (JNCIA-Junos) 92 questions Locked
- JN0-105Legacy Junos, Assoicate (JNCIA-JUNOS) 118 questions Locked
- Level
- Associate
- Valid for
- 3 years
Domains covered on the exam 7
- Networking Fundamentals15%
- Junos OS Fundamentals14%
- User Interfaces14%
- Configuration Basics14%
- Operational Monitoring and Maintenance14%
- Routing Fundamentals14%
- Routing Policy and Firewall Filters15%
- 1
A network architect is reviewing the performance metrics of a heavily utilized Juniper router during an active DDoS attack. The router is receiving a massive flood of ICMP echo requests targeted directly at its loopback interface.
Despite the massive influx of traffic directed at the router itself, transit traffic passing through the router to other networks experiences zero packet loss and normal latency.
Which architectural feature of Junos OS is primarily responsible for maintaining transit traffic performance during this localized attack?
flowchart LR RE[Routing Engine Control Plane] |Internal Link| PFE[Packet Forwarding Engine Forwarding Plane] PFE -->|Transit Traffic| PFE PFE -->|Exception Traffic| REShow answer details
Correct answer: C
Junos OS utilizes a strict separation of the control plane (RE) and forwarding plane (PFE). Traffic destined for the router (exception traffic) must cross an internal link from the PFE to the RE. This link has built-in rate limiters that prevent exception traffic floods (like ICMP or routing protocol attacks) from overwhelming the RE CPU, ensuring the PFE can continue processing transit traffic normally.
- 2
Which of the following is a primary function of the Routing Engine (RE) in Junos OS?
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Correct answer: C
The Routing Engine (RE) is responsible for all control plane functions, which includes running routing protocols, maintaining the routing tables (RIB), and determining the active routes to populate the forwarding table.
- 3
The foundational kernel of the Junos OS is based on an open-source operating system known for its stability and networking capabilities. Select the correct operating system kernel from the choices below.
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Correct answer: B
The Junos OS kernel is heavily based on the FreeBSD operating system. It provides the underlying environment for the routing protocols and management processes.
- 4
A network administrator is designing a new LAN topology for a branch office. They are deploying a 24-port Layer 2 Ethernet switch to connect workstations and a single router to connect the branch to the corporate WAN. How many broadcast domains and collision domains exist in this specific topology assuming all 24 switch ports are connected to active workstations and one port connects to the router?
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Correct answer: C
A Layer 2 switch creates a single broadcast domain for all connected devices (unless VLANs are configured) but isolates collision domains per port. With 24 workstations and 1 router connected to the switch, there are 25 active switch ports, resulting in 25 separate collision domains operating within 1 broadcast domain.
- 5
A corporate enterprise has been allocated the IPv4 network block 192.168.10.0/24. The network engineering team must segment this block to support six new departments.
Each department must have its own dedicated subnet. The largest department has 25 host devices that require IP addresses, while the others have fewer. The engineering team wants to use a single fixed-length subnet mask (FLSM) for all departments to simplify routing and management.
Which subnet mask should the team apply to meet the requirements while minimizing wasted IP addresses, and how many usable hosts will be available per subnet?
graph TD A[192.168.10.0/24] --> B[Subnet 1: .0/?] A --> C[Subnet 2: .32/?] A --> D[Subnet 3: .64/?] A --> E[Subnet 4: .96/?] A --> F[Subnet 5: .128/?] A --> G[Subnet 6: .160/?]Show answer details
Correct answer: B
To support 25 hosts, the subnet needs at least 5 host bits (2^5 - 2 = 30 usable hosts). A /27 mask provides 5 host bits and 3 subnet bits (from the /24 boundary). 3 subnet bits allow for 2^3 = 8 subnets, which satisfies the requirement for 6 subnets. Therefore, /27 is the optimal choice.
- 6
When a host on an Ethernet network needs to send data to another host on the same local subnet but only knows the destination's IPv4 address, which TWO of the following statements accurately describe the address resolution process? (Select TWO)
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Correct answer: A, C
Address Resolution Protocol (ARP) is used to map an IP address to a MAC address. The requesting host sends an ARP request to the broadcast MAC address (FF:FF:FF:FF:FF:FF) so all devices on the local segment process it.
When the target device receives the broadcast ARP request and recognizes its own IP address, it sends an ARP reply back to the requester. This reply is sent as a unicast frame directly to the requester's MAC address.
