JN0-281 Juniper Networks Certified Associate - Data Center (JNCIA-DC) Practice Questions
Prepare for JN0-281 with more than an answer.
- Exam fee
- $200 USD
- Level
- Associate
- Valid for
- 3 years
Domains covered on the exam 5
- Data Center Architectures15%
- Layer 2 Switching and VLANs20%
- Protocol-Independent Routing20%
- Data Center Routing Protocols BGP/OSPF30%
- High Availability15%
- 1
What is the primary function of a RIB group in Junos OS?
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Correct answer: B
RIB (Routing Information Base) groups allow routes learned by a protocol (like OSPF, BGP, or Interface routes) to be imported into multiple routing tables (e.g., inet.0 and a VRF table like blue.inet.0) simultaneously, facilitating route leaking between instances.
- 2
You need to configure load balancing on a Junos device to distribute traffic across multiple Equal-Cost Multi-Path (ECMP) links. Which two steps are required to achieve per-flow load balancing? (Select TWO)
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Correct answer: B, C
The load-balancing policy must be applied to the forwarding table (FIB) to take effect. This is done via 'set routing-options forwarding-table export '.
Despite the keyword 'per-packet' in the command, Junos OS performs per-flow load balancing by default on modern hardware when this action is applied. The configuration requires a policy setting 'then load-balance per-packet'.
- 3
What is the purpose of 'Martian' addresses in the context of Junos routing?
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Correct answer: B
Martian addresses are IP addresses that are reserved (e.g., 127.0.0.0/8, 240.0.0.0/4) or invalid for a specific context. Junos maintains a default table of these addresses and will reject routes to them to ensure security and proper routing behavior.
- 4
A network architect is designing a new IP fabric for a data center. The design requires predictable latency and a non-blocking architecture for east-west traffic. Which topology should be selected to best meet these requirements?
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Correct answer: D
A spine-and-leaf architecture (also known as a Clos network) is designed specifically for modern data centers to optimize east-west traffic. Every leaf switch connects to every spine switch, ensuring a consistent number of hops (predictable latency) and high bandwidth availability (non-blocking) between any two devices connected to the leaf layer.
graph TD subgraph Spine Layer S1[Spine 1] S2[Spine 2] end subgraph Leaf Layer L1[Leaf 1] L2[Leaf 2] L3[Leaf 3] end S1 --- L1 S1 --- L2 S1 --- L3 S2 --- L1 S2 --- L2 S2 --- L3 - 5
In an EVPN-VXLAN data center architecture, which component is responsible for the control plane operations that handle MAC address learning and reachability information distribution?
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Correct answer: A
This statement refers to EVPN. In an EVPN-VXLAN architecture, EVPN (Ethernet VPN) serves as the control plane. It uses Multiprotocol BGP (MP-BGP) to exchange MAC addresses and IP prefix information between VTEPs, replacing the traditional flood-and-learn mechanism of the data plane with a robust BGP-based control plane.
- 6
Which TWO characteristics accurately describe the underlay network in a modern IP fabric data center design? (Select TWO)
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Correct answer: A, B
The underlay network is the physical infrastructure that ensures IP reachability between loopback interfaces of the spine and leaf switches, serving as the transport for the overlay.
Underlay networks commonly use robust Layer 3 protocols like EBGP or OSPF to manage loop-free paths and ECMP load balancing between spines and leaves.
