JN0-106 Sample Questions & Answers
Fundamental networking elements and routing policy with firewall filters edge out the rest slightly, alongside the core elements of Junos OS, the Junos interface, device configuration basics, and monitoring and maintaining devices day to day.
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- Question 1Intermediate
Networking Fundamentals · Longest match routing
A Junos device receives a packet destined for the IP address 10.1.5.50. The routing table contains multiple active routes that encompass this destination. Based on the longest match routing principle, which of the following routes will the router select to forward the packet?
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Correct answer: C
Routers use the longest prefix match algorithm to select the best route among overlapping subnets. The route with the longest subnet mask (highest number of network bits) is the most specific. Among /8, /16, /24, and /0, the /24 route is the most specific match for 10.1.5.50.
- Question 2Beginner
Networking Fundamentals · Connection-oriented vs. connectionless protocols
True or False: Transmission Control Protocol (TCP) is an example of a connectionless protocol because it relies on the underlying IP layer to establish the path before data transmission begins.
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Correct answer: B
False. TCP is a connection-oriented protocol because it establishes a logical connection (via the 3-way handshake) before sending data, ensuring reliability and ordered delivery. UDP, in contrast, is a connectionless protocol.
- Question 3Beginner
Networking Fundamentals · Decimal to binary conversion
During a network assessment, you need to configure an interface with an IP address that ends with the decimal value 192 in the last octet. What is the correct binary representation of the decimal number 192?
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Correct answer: C
In binary, the octet places represent 128, 64, 32, 16, 8, 4, 2, 1. To get 192, you add 128 + 64. Therefore, the first two bits are 1s, and the remaining six bits are 0s, resulting in 11000000.
pie title Decimal 192 Binary Breakdown "128 bit (1)" : 128 "64 bit (1)" : 64 "Remaining 6 bits (0s)" : 0 - Question 4Intermediate
Junos OS Fundamentals · Control and forwarding planes
In the Junos OS software architecture, which component is strictly responsible for maintaining routing protocols, managing chassis components, and providing the user interface?
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Correct answer: C
The Routing Engine (RE) represents the control plane in the Junos OS architecture. It runs the Junos OS kernel, handles routing protocols (like OSPF and BGP), manages system components, and provides the CLI/J-Web interfaces.
- Question 5BeginnerSelect 2
Junos OS Fundamentals · Exception traffic
In Junos OS architecture, certain types of traffic cannot be processed solely by the Packet Forwarding Engine (PFE) and must be passed to the Routing Engine (RE). Which TWO of the following are examples of this "exception traffic"? (Select TWO)
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Correct answers: B, D
Traffic addressed directly to the router (such as pinging the router's IP or SSH sessions) is considered exception traffic and must be forwarded to the RE for processing.
Routing protocol updates like OSPF Hellos or BGP keepalives are destined for the router itself to maintain the control plane state, making them exception traffic handled by the RE.
- Question 6Intermediate
Junos OS Fundamentals · Transit traffic processing
How does the Junos OS architecture handle transit traffic processing to ensure high performance and prevent control plane exhaustion?
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Correct answer: B
In Junos OS, transit traffic (traffic passing through the router to another destination) is handled entirely by the Packet Forwarding Engine (PFE). The PFE uses the forwarding table provided by the RE to make hardware-based forwarding decisions without RE intervention, ensuring high throughput.
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