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Juniper Networks Certified Associate - Data Center (JNCIA-DC) Free Sample Questions

Description

Covers traditional and spine-leaf data center architectures, Ethernet switching and VLAN configuration, static, aggregate and generated routes, and link aggregation and graceful restart.

12 free sample questions120 in the full practice test

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JN0-281 Sample Questions

  1. Question 1

    Intermediate

    Data Center Architectures · IP fabric Architectures (Spine/Leaf)

    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?

    Answer and explanation

    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

  2. Question 2

    Intermediate

    Data Center Architectures · Ethernet VPN–Virtual Extensible LAN (EVPN-VXLAN) basics/purpose

    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?

    Answer and explanation

    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.

  3. Question 3

    IntermediateMultiple answers

    Data Center Architectures · Overlay Network vs. Underlay Network

    Which TWO characteristics accurately describe the underlay network in a modern IP fabric data center design? (Select TWO)

    Answer and explanation

    Correct answers: 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.

  4. Question 4

    Beginner

    Layer 2 Switching and VLANs · Port modes

    A Juniper administrator is configuring a QFX Series switch. They need to configure a specific interface to carry traffic for multiple VLANs to a connected server that supports 802.1Q tagging. Which configuration command correctly sets the interface mode?

    Answer and explanation

    Correct answer: B

    In Junos OS, to allow an interface to carry multiple VLANs using 802.1Q tagging, the interface mode must be set to 'trunk'. The command 'set interfaces unit 0 family ethernet-switching interface-mode trunk' accomplishes this.

  5. Question 5

    Beginner

    Layer 2 Switching and VLANs · Ethernet switching/bridging concepts and operations

    While troubleshooting Layer 2 connectivity on a Juniper switch, you verify the contents of the Ethernet switching table. What information is primarily contained in this table?

    Answer and explanation

    Correct answer: C

    The Ethernet switching table (often called the MAC address table) maps MAC addresses to the specific ports/interfaces where they were learned and associates them with their respective VLANs to facilitate Layer 2 forwarding.

  6. Question 6

    Intermediate

    Layer 2 Switching and VLANs · Integrated Routing and Bridging (IRB)

    You are configuring an Integrated Routing and Bridging (IRB) interface on a QFX switch to provide Layer 3 gateway services for VLAN 100. Which configuration step associates the Layer 3 logical interface with the Layer 2 VLAN?

    Answer and explanation

    Correct answer: B

    To link a VLAN to a Layer 3 IRB interface in Junos, you must configure the 'l3-interface' statement within the VLAN configuration hierarchy, pointing to the specific IRB logical unit (e.g., irb.100).

    graph LR subgraph Configuration V[VLAN 100] -- references --> I[irb.100] I -- has --> IP[IP Address] end

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