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100+ Free JNCDS-DC Practice Questions

Pass your Juniper Networks Certified Design Specialist, Data Center (JNCDS-DC) exam on the first try — instant access, no signup required.

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Key Facts: JNCDS-DC Exam

65

Exam Questions

Juniper Networks

90 min

Exam Duration

Juniper Networks

$300

Exam Fee

Juniper Networks

3 years

Certification Validity

Juniper Networks

~30%

EVPN-VXLAN Weight

Largest exam domain

JN0-1302

Exam Code

Juniper Networks

The JNCDS-DC exam has 65 questions in 90 minutes. Key topics: EVPN-VXLAN design (~30%), IP fabric underlay (~20%), data center architectures (~20%), Apstra automation (~15%), and security/services (~15%). Prerequisite: JNCDA recommended, with JNCIS-DC or equivalent experience. Exam fee: $300 via Pearson VUE. Valid 3 years.

Sample JNCDS-DC Practice Questions

Try these sample questions to test your JNCDS-DC exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A network designer is planning an IP fabric for a new data center. Which underlay routing protocol is most commonly recommended for leaf-spine IP fabric deployments due to its scalability and fast convergence?
A.eBGP with each leaf and spine in a unique ASN
B.OSPF with all devices in a single area
C.IS-IS with wide metrics enabled
D.RIP version 2 with route summarization
Explanation: eBGP is the most commonly recommended underlay protocol for leaf-spine IP fabrics. Assigning each leaf and spine a unique ASN enables clean eBGP peering, simple loop prevention, and fast convergence. Juniper's QFX-based IP fabrics rely on this design. OSPF is viable but lacks the operational simplicity and scalability of eBGP at large scale.
2In an EVPN-VXLAN IP fabric, which EVPN route type is used to advertise MAC and IP binding information learned from tenant endpoints?
A.EVPN Type 2 (MAC/IP Advertisement Route)
B.EVPN Type 3 (Inclusive Multicast Ethernet Tag Route)
C.EVPN Type 5 (IP Prefix Route)
D.EVPN Type 1 (Ethernet Auto-Discovery Route)
Explanation: EVPN Type 2 routes carry both MAC and IP address information for tenant endpoints, enabling distributed MAC and ARP learning across the fabric. This eliminates traditional flood-and-learn behavior and allows VTEPs to build their forwarding tables from the BGP control plane.
3When designing a data center using EVPN-VXLAN with an asymmetric IRB model, what is a key characteristic of the asymmetric approach?
A.Both routing and bridging occur on the ingress leaf, requiring all VNIs to be provisioned on every leaf
B.Routing occurs only on spine nodes, leaving leaf nodes as pure Layer 2 gateways
C.Each leaf handles only L2 bridging; a dedicated routing device provides inter-VLAN forwarding
D.Routing is handled by a centralized route reflector outside the fabric
Explanation: In the asymmetric IRB model, the ingress leaf performs both the routing (L3 lookup) and bridging into the destination VNI. This means every leaf must have all tenant VNIs locally configured, which can increase VLAN/VNI scale requirements. The benefit is simpler design with fewer hops for intra-fabric traffic.
4A designer needs to provide multi-homing with active-active forwarding for a server connected to two QFX leaf switches in an EVPN-VXLAN fabric. Which EVPN feature enables this design?
A.EVPN Ethernet Segment Identifier (ESI) with All-Active multi-homing
B.VRRP with preemption disabled on both leaf switches
C.Spanning Tree Protocol with RSTP on both uplinks
D.BGP Add-Path to advertise duplicate MAC entries
Explanation: EVPN ESI multi-homing with All-Active mode allows a CE device to be connected to two PE (leaf) devices and forward traffic over both links simultaneously. ESI labels identify the Ethernet segment, and EVPN Type 1 and Type 2 routes coordinate loop prevention and aliasing across the fabric.
5Which Juniper platform is specifically designed as a high-density, low-latency top-of-rack (ToR) switch optimized for IP fabric leaf deployments?
A.QFX5120
B.MX480
C.SRX4600
D.EX9200
Explanation: The QFX5120 series is Juniper's purpose-built ToR switch optimized for data center leaf roles in IP fabric deployments. It provides high port density (48x25G or 48x10G with 8x100G uplinks) and hardware-accelerated VXLAN/EVPN support at low latency. The MX is a service router, the SRX is a firewall, and the EX9200 is a campus core switch.
6In a Juniper Apstra-managed data center, what is the primary function of the Apstra Intent-Based Networking (IBN) system?
A.Translate high-level network intent into device-specific configurations and continuously validate the network state against that intent
B.Provide Layer 7 application load balancing across data center servers
C.Replace the BGP control plane with a centralized routing engine
D.Monitor physical server CPU and memory utilization
Explanation: Juniper Apstra is an Intent-Based Networking system that allows operators to define the desired network state (intent) at a high level. Apstra then automatically generates vendor-specific device configurations and continuously validates that the running network matches the intent, providing closed-loop assurance. It supports multi-vendor environments.
7A data center design requires BUM (Broadcast, Unknown Unicast, and Multicast) traffic handling in an EVPN-VXLAN fabric without using multicast in the underlay. Which mechanism should the designer select?
A.Ingress replication (head-end replication) using EVPN Type 3 routes to signal VTEP membership
B.PIM-SM with a rendezvous point on each spine
C.IGMP snooping on all leaf switches
D.Static multicast groups configured per VNI
Explanation: Ingress replication (also called head-end replication) is the recommended BUM handling mechanism when multicast is unavailable in the underlay. Each VTEP builds a list of remote VTEPs for each VNI using EVPN Type 3 routes and unicast-replicates BUM frames to each remote VTEP. This simplifies underlay requirements by eliminating the need for multicast routing.
8When designing a Data Center Interconnect (DCI) solution using EVPN-VXLAN across two geographically separated data centers, what is the role of a gateway device at each site?
A.Terminate site-local VXLANs and re-originate MAC/IP routes into the remote fabric's BGP EVPN domain
B.Provide DHCP relay services for all tenant VLANs across the WAN link
C.Act as a BGP route reflector for all leaf switches at both sites
D.Perform MPLS label distribution between the two data centers
Explanation: In a DCI design, the gateway (sometimes called a Border Leaf or DCI GW) terminates local EVPN-VXLAN tunnels, performs MAC/IP route leaking between the local fabric's BGP domain and the inter-DC BGP session, and re-originates reachability into the remote site. This allows hosts in both DCs to communicate while maintaining separate control-plane domains per site.
9In a Juniper QFX-based IP fabric, what is the purpose of the `add-path` BGP capability when configured on spine route reflectors?
A.Allow the spine to advertise multiple equal-cost paths for the same NLRI to leaf switches, enabling ECMP across the fabric
B.Enable BGP to carry MPLS labels along with IP prefixes
C.Force all leaf switches to prefer routes learned from a specific spine
D.Prevent BGP best-path selection from removing duplicate routes
Explanation: BGP Add-Path (RFC 7911) allows a BGP speaker to advertise multiple paths for the same prefix, each with a unique path identifier. When spines act as route reflectors, Add-Path is critical to preserve multiple equal-cost paths to leaf loopbacks, enabling downstream ECMP across the fabric. Without Add-Path, a route reflector would only re-advertise its single best path.
10A designer is evaluating the symmetric IRB model for an EVPN-VXLAN fabric. Compared to asymmetric IRB, what is the key advantage of symmetric IRB?
A.Not all tenant VNIs need to be provisioned on every leaf switch, reducing VNI scale requirements
B.Symmetric IRB eliminates the need for BGP EVPN and relies solely on data-plane learning
C.Symmetric IRB reduces the VXLAN encapsulation overhead to zero
D.Symmetric IRB requires only a single spine node for the entire fabric
Explanation: In symmetric IRB, routing occurs at both ingress and egress leaves via a dedicated L3 VNI (the IRB VNI). Because the egress leaf performs the final routing, not every leaf needs all tenant L2 VNIs — only the L3 VNI must be consistent. This dramatically reduces VNI scale requirements in large multi-tenant fabrics.

About the JNCDS-DC Exam

The JNCDS-DC (JN0-1302) validates advanced ability to design data center networks using Juniper technologies. It covers IP fabric architecture using leaf-spine topology with eBGP underlay, EVPN-VXLAN overlay design including symmetric/asymmetric IRB and multi-homing, Juniper Apstra Intent-Based Networking, data center security with micro-segmentation, and data center interconnect (DCI) design.

Questions

65 scored questions

Time Limit

90 minutes

Passing Score

Not publicly disclosed (estimated 60-70%)

Exam Fee

$300 (Juniper Networks / Pearson VUE)

JNCDS-DC Exam Content Outline

~20%

Data Center Architectures and Design Concepts

Leaf-spine topology design, Clos networks, 2-tier vs. 3-tier architectures, multi-pod fabrics with super-spine tier, design trade-offs for scalability and availability

~30%

EVPN-VXLAN Design

All five EVPN route types, symmetric IRB with L3 VNI, asymmetric IRB, anycast gateway for distributed routing, ESI multi-homing (All-Active), BUM traffic handling via ingress replication

~20%

IP Fabric Underlay Design

eBGP underlay with unique per-device ASNs, spine route reflectors with BGP Add-Path, ECMP across fabric, /31 point-to-point addressing, jumbo MTU for VXLAN overhead

~15%

Data Center Automation with Juniper Apstra

Apstra IBN platform, Blueprint concepts and lifecycle, logical devices and rack definitions, device agents for multi-vendor support, IBA custom analytics, ZTP, anomaly detection

~15%

Security, DCI, and Advanced Services

Micro-segmentation with vSRX, VRF-based service chaining, multi-tenant design, DCI border leaf design with EVPN route leaking, hybrid cloud (AWS Direct Connect), PFC/DCB for NVMe-oF

How to Pass the JNCDS-DC Exam

What You Need to Know

  • Passing score: Not publicly disclosed (estimated 60-70%)
  • Exam length: 65 questions
  • Time limit: 90 minutes
  • Exam fee: $300

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

JNCDS-DC Study Tips from Top Performers

1Master the five EVPN route types: Type 1 (Auto-Discovery), Type 2 (MAC/IP), Type 3 (IMET), Type 4 (Ethernet Segment), Type 5 (IP Prefix)
2Know symmetric vs. asymmetric IRB: asymmetric requires all VNIs on every leaf; symmetric uses an L3 VNI and scales better
3Understand BGP Add-Path: required on spine route reflectors to preserve multiple ECMP paths to leaf loopbacks
4Study Apstra Blueprint lifecycle: logical devices → rack definitions → blueprint commit → device agent deployment
5Know VXLAN MTU impact: 50 bytes of overhead requires jumbo frame MTU (9100-9216) on fabric links
6Practice `show evpn database`, `show bgp summary evpn`, and `show route table bgp.evpn.0` for troubleshooting questions
7Understand ESI multi-homing: Type 1 routes for aliasing, Type 4 for Designated Forwarder election

Frequently Asked Questions

What is the JNCDS-DC (JN0-1302) exam?

The JNCDS-DC is Juniper's Data Center Design Specialist certification, exam code JN0-1302. It validates ability to design scalable data center networks using Juniper platforms including QFX switches, IP fabric with eBGP, EVPN-VXLAN overlays, and Juniper Apstra IBN. The exam has 65 questions delivered in 90 minutes through Pearson VUE.

What are the prerequisites for JNCDS-DC?

Juniper recommends JNCDA (Design Associate) certification and JNCIS-DC or equivalent data center operational experience. Hands-on experience with Juniper QFX switches, EVPN-VXLAN configuration, and data center design is strongly recommended before attempting the JNCDS-DC exam.

How much does the JNCDS-DC exam cost?

The JNCDS-DC exam costs $300 USD per attempt, administered through Pearson VUE testing centers or online proctored. The certification is valid for 3 years. Recertification is required before expiration by passing the current version of the exam or a higher-level exam in the same track.

What QFX platforms should I know for the JNCDS-DC?

Focus on QFX5120 (ToR leaf), QFX5200 (leaf/spine), QFX10002 and QFX10008 (high-scale spine). Understand the merchant silicon ASIC-based hardware forwarding, cut-through switching, and how VXLAN encapsulation/decapsulation is performed in hardware. Also understand when to select vQFX for lab environments.

How long should I study for the JNCDS-DC?

Most candidates with JNCIS-DC experience need 80-120 hours of study over 3-6 months. Priority areas: EVPN-VXLAN design (30%), IP fabric underlay (20%), and Juniper Apstra (15%). Hands-on lab time with QFX virtual switches and Apstra trial environments is highly recommended.