Juniper JN0-683 Exam Dumps & Practice Test Questions
Question 1
To verify that VXLAN traffic from the physical interface xe-0/0/12 is being encapsulated by the logical VTEP interface vtep.32770 and is successfully sent to a remote leaf node, which command is the most appropriate for monitoring the traffic flow?
A. Monitor traffic on the xe-0/0/12 interface
B. Display detailed information about the vtep.32770 interface
C. Show a summary of the vtep.32770 interface
D. Display statistics of the vtep.32770 interface in terse mode
Correct Answer: B
Explanation:
When working with VXLAN on a Juniper-based platform or similar systems, it's important to confirm that VXLAN encapsulation is functioning as expected—particularly that VXLAN traffic from a physical interface (like xe-0/0/12) is being encapsulated by the logical VTEP interface (vtep.32770) and forwarded correctly.
In this context, each interface type offers a specific level of diagnostic output:
Physical interface (xe-0/0/12) shows Layer 1/2 activity.
VTEP interface (vtep.32770) handles VXLAN encapsulation and acts as a logical VXLAN Tunnel Endpoint.
Monitor or show commands differ in their granularity and focus.
Let’s review the options:
A. Monitor traffic on the xe-0/0/12 interface: This command would let you passively observe traffic entering or leaving the physical interface. While it can show whether packets are being received or transmitted, it doesn’t provide insight into VXLAN encapsulation, the VNI being used, or whether the encapsulation is correctly occurring via the VTEP interface. It’s low-level and not sufficient for VXLAN-level verification.
B. Display detailed information about the vtep.32770 interface: This is the correct option. Displaying detailed information about the VTEP interface (vtep.32770) will show encapsulation statistics, such as VNI mappings, packet counters, and the status of tunnels to remote VTEPs. This data is essential for confirming that the interface is actively encapsulating traffic and sending it to the remote VXLAN endpoint.
C. Show a summary of the vtep.32770 interface: A summary view may include basic operational status, but it typically lacks sufficient detail about encapsulation metrics, such as bytes in/out, encapsulated packets, or VNI-specific statistics. It is useful for a quick status check but not adequate for full troubleshooting.
D. Display statistics of the vtep.32770 interface in terse mode: Terse output typically includes only interface up/down status and basic packet counts. It’s faster but too shallow for debugging VXLAN encapsulation paths and verifying inter-VTEP communication.
Therefore, the best approach to confirm that VXLAN encapsulation is occurring correctly through the logical VTEP interface is to display detailed information for vtep.32770, making B the correct answer.
Question 2
Which two protocols are used in the control plane to establish VXLAN communication between devices? (Choose two.)
A. MBGP
B. PIM-SM
C. OSPF
D. IS-IS
Correct Answer: A, B
Explanation:
VXLAN can operate in two modes: flood-and-learn (data-plane learning) and control-plane learning (typically via a protocol such as EVPN over BGP). Control-plane-based VXLAN—now the preferred approach in modern data center networks—relies on protocols that can signal VXLAN tunnel endpoints (VTEPs), VNI mappings, and MAC address mobility.
Two widely used control plane protocols for VXLAN are:
A. MBGP (Multiprotocol BGP): Correct. MBGP, or more specifically EVPN over MP-BGP, is the industry-standard control plane for VXLAN deployments. MP-BGP distributes VXLAN-related routing information, including MAC addresses and IP prefixes, across VTEPs. EVPN enables scalable and efficient distribution of Layer 2 and Layer 3 reachability data without relying on flood-and-learn mechanisms. It supports features like MAC learning, ARP suppression, and seamless host mobility.
B. PIM-SM (Protocol Independent Multicast - Sparse Mode): Correct. In VXLAN multicast-based environments—particularly when using flood-and-learn mode—multicast is required to replicate broadcast, unknown unicast, and multicast (BUM) traffic across multiple VTEPs. PIM-SM is used to build the multicast distribution trees that transport this BUM traffic. While not used for routing or signaling in the control plane, it is still considered part of the VXLAN control architecture when multicast underlays are deployed.
Now, the incorrect options:
C. OSPF: While OSPF may be used as an IGP in the underlay network, it does not participate in VXLAN-specific control plane operations. OSPF establishes basic IP reachability between VTEPs but does not manage VXLAN tunneling or MAC advertisement.
D. IS-IS: Similar to OSPF, IS-IS can also provide underlay routing but has no role in VXLAN control-plane signaling. It cannot advertise MAC-to-VTEP mappings or participate in EVPN operations.
Therefore, the correct answers are A and B, as MP-BGP is the core protocol for EVPN VXLAN control plane, and PIM-SM is used in multicast VXLAN deployments to handle broadcast replication.
Question 3
Which two methods can be used to export telemetry data using the Junos Telemetry Interface (JTI)? (Choose two.)
A. SNMP
B. gRPC
C. UDP
D. REST
Correct Answers: B, C
Explanation:
The Junos Telemetry Interface (JTI) is a high-performance streaming telemetry feature available in Juniper devices running Junos OS. JTI provides real-time, fine-grained visibility into network operations by exporting detailed operational and performance data from Junos devices to external collectors or telemetry receivers.
JTI supports two primary data export mechanisms:
gRPC (Google Remote Procedure Call):
This is the primary and most commonly used protocol for JTI telemetry data export. It is a modern, efficient, and bi-directional communication protocol that allows devices to stream data in a structured format (often using Protocol Buffers, or Protobuf). Junos devices use gRPC to send continuous streams of telemetry data to collectors. gRPC also supports secure communication via TLS, and it allows subscriptions to data models defined using YANG schemas.UDP (User Datagram Protocol):
JTI also supports exporting data using UDP for statistical counters, particularly for systems that prefer lightweight, fast data delivery without the overhead of session management. This is typically used in push-based telemetry, where telemetry data is sent periodically to a fixed collector. While not as robust or secure as gRPC, UDP is still supported in JTI for specific use cases where low-latency and simplicity are prioritized.
Let’s now consider the incorrect options:
A (SNMP): While SNMP is a well-known protocol for network monitoring, it is not part of JTI’s architecture. SNMP operates on a polling mechanism and is considered legacy in comparison to the streaming model of JTI. SNMP lacks the real-time granularity and flexibility that JTI provides and is not supported as a telemetry export method under JTI.
D (REST): REST APIs are used for configuration and control-plane interaction with Junos devices, such as retrieving or updating device settings. However, REST is not used to export streaming telemetry data in JTI. REST is based on HTTP and is not suitable for high-frequency, real-time telemetry streaming.
Thus, the two valid telemetry export protocols supported by JTI are gRPC (B) and UDP (C).
Question 4
Which of the following is true regarding a collapsed fabric EVPN-VXLAN network architecture?
A. Fully meshed, back-to-back links are necessary between the spine devices.
B. Border leaf devices handle the border gateway functions.
C. It allows multiple vendors in the fabric, provided all spine devices are Juniper devices with L2 VTEPs.
D. Resiliency is enhanced by using Virtual Chassis at the leaf layer.
Correct Answer: B
Explanation:
The collapsed fabric architecture in EVPN-VXLAN is an approach in which traditional roles of spine and leaf layers may be consolidated into fewer devices—often combining both roles into single devices for smaller or mid-sized deployments. In such an architecture, fewer switches are used, and the VXLAN control plane is still handled by BGP EVPN.
A key aspect of the collapsed fabric is the use of border leaf switches. These devices not only serve end hosts (like regular leaf nodes) but also act as gateways between the VXLAN fabric and external networks, including traditional Layer 3 domains, Internet connections, or data center interconnects.
Let’s evaluate each option:
A (Fully meshed, back-to-back links are necessary between the spine devices): This is incorrect. In a collapsed fabric, spines and leafs are often combined, reducing the need for traditional spine-spine meshing. Fully meshed spine links are typical of non-collapsed, three-tier architectures, not collapsed designs. Collapsed fabric simplifies the topology to reduce cost and complexity.
B (Border leaf devices handle the border gateway functions): This is the correct statement. In a collapsed EVPN-VXLAN fabric, border leaf switches are responsible for route leaking, external connectivity, and VXLAN-to-non-VXLAN translations. These switches serve a dual role—connecting both to the internal VXLAN fabric and to the outside network. This makes them central to any collapsed fabric topology.
C (It allows multiple vendors in the fabric, provided all spine devices are Juniper devices with L2 VTEPs): This is misleading and incorrect. While multi-vendor EVPN-VXLAN fabrics can be built, doing so requires standards compliance across all platforms. There's no requirement that spine devices must be Juniper L2 VTEPs; in fact, in VXLAN EVPN, VTEPs typically perform L3 routing, especially for inter-subnet forwarding. The concept of limiting to "L2 VTEPs" is flawed and not relevant to interoperability.
D (Resiliency is enhanced by using Virtual Chassis at the leaf layer): This is a general network design practice, but not specific to or required in a collapsed fabric EVPN-VXLAN architecture. While Virtual Chassis or EVPN multihoming can improve resiliency, they are implementation choices, not architectural truths about collapsed fabric.
Therefore, the correct answer is B: Border leaf devices handle the border gateway functions in a collapsed EVPN-VXLAN fabric.
Question 5
In a VPN environment using EVPN, which parameter determines how a received route is associated with the correct local VPN routing table?
A. Route-distinguisher
B. VLAN ID
C. Route-target community
D. VNI
Correct Answer: C
Explanation:
In EVPN (Ethernet VPN) and other BGP-based VPN technologies like MPLS Layer 3 VPNs, route propagation and segregation between tenants or VPNs are handled using a combination of Route Distinguisher (RD) and Route Target (RT). While these concepts are often used together, they serve different purposes in the control plane.
To understand the question, it’s important to differentiate between route identification and route import/export policies:
The Route Distinguisher (RD) is used to make a route unique across different VPNs by adding a distinguishing prefix to the route, making overlapping IP addresses in different VRFs distinguishable in the global BGP table. However, the RD does not determine how or where the route is used locally.
The Route Target (RT) is a BGP extended community attribute used to define import/export policies. It tells a receiving PE device whether it should import a specific route into a given VRF (VPN Routing and Forwarding instance). In short, the RT is what maps the received route to the local routing table.
Let’s evaluate each option:
A. Route-distinguisher: This is used to make the route unique in the BGP table but does not control which VRF the route is imported into.
B. VLAN ID: The VLAN ID operates at Layer 2 and is used for local segmentation on switches. It does not play a role in VPN route mapping.
C. Route-target community: Correct. This BGP extended community tag defines import/export policies that determine which routes are included in a VRF. For example, a VRF configured to import routes with RT 100:1 will import any BGP route carrying that community value. This mechanism directly controls route-to-VRF mapping.
D. VNI (VXLAN Network Identifier): The VNI defines the Layer 2 or Layer 3 overlay segment in VXLAN. While it is used in EVPN to associate traffic with a particular tenant or bridge domain, it does not dictate BGP route import behavior in the control plane.
Therefore, the correct answer is C, because route-target communities are the parameters that map incoming BGP EVPN routes to the correct local VPN or VRF routing table.
Question 6
In designing an EVPN-VXLAN architecture for a data center expected to begin with fewer than 50 switches and scale to 250 switches with up to 1024 VLANs, which two statements are accurate? (Choose two.)
A. Asymmetric routing routes traffic on the egress switch.
B. Symmetric routing is better suited for higher scalability.
C. Asymmetric routing is easier to monitor due to the transit VNI.
D. Symmetric routing requires an additional VLAN with an IRB interface for each L3 VRF instance.
Correct Answers: B, D
Explanation:
In an EVPN-VXLAN fabric, Layer 3 routing across VXLAN segments can be implemented using either asymmetric or symmetric routing models. These models define where inter-subnet routing occurs and how it scales within a data center fabric.
Let’s break down the two models:
Asymmetric routing: Inter-subnet traffic is routed at the ingress leaf switch, and the resulting packet is bridged in the destination VXLAN. This approach is simpler but becomes less scalable as the number of VLANs or VNIs increases, because every leaf switch must support all VLANs and routing interfaces, even if they are not locally used.
Symmetric routing: Traffic is first routed at the ingress VTEP to a Layer 3 VNI, then routed again at the egress VTEP to the destination VLAN. This approach decouples VLANs from being present on every leaf, enhancing scalability and routing efficiency.
Let’s evaluate the statements:
A. Asymmetric routing routes traffic on the egress switch: Incorrect. In asymmetric routing, routing takes place at the ingress switch only. The ingress VTEP performs inter-VLAN routing, and then forwards the traffic to the destination VTEP, which only performs bridging.
B. Symmetric routing is better suited for higher scalability: Correct. Symmetric routing scales better because each VTEP only needs to support local VLANs, and routing is done using common Layer 3 VNIs. This reduces configuration overhead and improves control-plane efficiency in large-scale environments, such as the one described (250 switches and 1024 VLANs).
C. Asymmetric routing is easier to monitor due to the transit VNI: Incorrect. Asymmetric routing does not use a transit VNI. Only symmetric routing uses a dedicated Layer 3 VNI for inter-VRF traffic, which actually makes symmetric routing easier to monitor, as routing traffic is tagged distinctly.
D. Symmetric routing requires an additional VLAN with an IRB interface for each L3 VRF instance: Correct. In symmetric routing, each L3 VRF is associated with a Layer 3 VNI, and each leaf that needs to perform routing for that VRF must have a corresponding IRB interface (Integrated Routing and Bridging). This means additional configuration is required, but it supports greater scalability.
Therefore, the correct answers are B and D, as symmetric routing is ideal for large-scale EVPN-VXLAN deployments, and it requires a dedicated IRB interface and Layer 3 VNI per VRF.
Question 7
In a VXLAN deployment, which command is used to check the encapsulation status of the VTEP (Virtual Tunnel Endpoint) on a Juniper device?
A. show vxlan interface vtep
B. show vxlan tunnel details
C. show interfaces vtep.32770
D. show vtep encapsulation status
Correct Answer: C
Explanation:
In a VXLAN deployment on Juniper Networks devices running Junos OS, each Virtual Tunnel Endpoint (VTEP) is implemented as a logical interface—often named something like vtep.32770. This interface is responsible for encapsulating and decapsulating Layer 2 Ethernet frames in VXLAN headers so they can be transmitted across an underlying Layer 3 IP network.
To verify the VTEP’s encapsulation status, the appropriate command is:
show interfaces vtep.32770
This command provides key operational data about the VTEP interface, including:
Interface status (up/down)
Encapsulation type (VXLAN)
MAC and IP information
Packet statistics
Tunnel-related metrics
This interface-specific command gives detailed insight into whether the VTEP is operational and correctly performing VXLAN encapsulation.
Now, let’s look at the other options:
A (show vxlan interface vtep): This is not a valid Junos command. While the name looks plausible, Junos CLI does not include a show vxlan interface vtep command in its syntax.
B (show vxlan tunnel details): This command does not exist in standard Junos syntax either. While VXLAN tunnel information can be viewed, it is usually accessed via show evpn or show interfaces commands related to the actual VTEP interfaces.
D (show vtep encapsulation status): Again, this command is not valid on Junos devices. There’s no such syntax that directly provides encapsulation status using this format.
Therefore, the most appropriate and accurate command to verify VTEP encapsulation status is show interfaces vtep.32770, making C the correct answer.
Question 8
What is the primary purpose of EVPN in an EVPN-VXLAN architecture?
A. To handle the encapsulation of Layer 2 traffic over a Layer 3 network
B. To route multicast traffic across VXLAN tunnels
C. To provide VXLAN encapsulation on physical interfaces
D. To enable Layer 3 VPN services for VTEPs
Correct Answer: A
Explanation:
In a VXLAN-EVPN architecture, the role of EVPN (Ethernet VPN) is critical to enabling advanced functionality and scalability across modern data center fabrics.
The primary function of EVPN is to serve as the control plane for VXLAN. While VXLAN provides Layer 2 over Layer 3 encapsulation (i.e., it allows Ethernet frames to be tunneled over an IP network), it does not inherently define a scalable or efficient control plane mechanism for learning MAC and IP addresses. Traditionally, VXLAN used flood-and-learn mechanisms, which are inefficient and prone to scalability issues.
EVPN solves this by replacing flood-and-learn with a BGP-based control plane. It allows VTEPs (Virtual Tunnel Endpoints) to advertise MAC addresses, IP-to-MAC bindings (ARP entries), and Layer 3 reachability information using BGP (Border Gateway Protocol). This ensures that:
MAC learning is control-plane-based, not dependent on flooding.
Host mobility is supported via EVPN MAC Mobility features.
Scalability is improved due to BGP route aggregation and route types.
So, A (To handle the encapsulation of Layer 2 traffic over a Layer 3 network) is correct because EVPN enables this encapsulation to happen intelligently and scalably, forming the foundation of modern VXLAN deployments.
Now let’s examine the other options:
B (To route multicast traffic across VXLAN tunnels): While multicast traffic can traverse VXLAN tunnels using EVPN, this is not the primary function of EVPN. Instead, multicast handling depends on BUM (Broadcast, Unknown Unicast, and Multicast) replication modes, such as head-end replication or multicast trees managed via control plane.
C (To provide VXLAN encapsulation on physical interfaces): This function is handled by the VXLAN data plane, not EVPN. VXLAN encapsulation occurs at the VTEP, and this involves the underlying physical or logical interface configurations.
D (To enable Layer 3 VPN services for VTEPs): This is misleading. While EVPN can carry Layer 3 information (such as in Type 5 routes), the architecture's goal is to extend Layer 2 segments across a Layer 3 fabric. True Layer 3 VPNs are typically handled via IP-VPN (RFC 4364), not EVPN in the VXLAN context.
Therefore, the correct and primary role of EVPN in a VXLAN deployment is A: to handle the encapsulation of Layer 2 traffic over a Layer 3 network in a scalable and efficient manner using a control-plane approach.
Question 9
Which two technologies are commonly used to provide Layer 3 routing capabilities in a VXLAN-based network architecture? (Choose two.)
A. MP-BGP
B. OSPF
C. IS-IS
D. RSTP
Correct Answers: A, B
Explanation:
VXLAN (Virtual Extensible LAN) was primarily designed as a Layer 2 overlay technology to address VLAN scalability limitations. However, in modern data center environments, Layer 3 functionality must be tightly integrated with VXLAN to enable inter-subnet communication, tenant separation, and dynamic route learning. This integration is typically achieved through control plane protocols that support Layer 3 routing within the VXLAN fabric.
Let’s analyze each of the listed technologies:
A. MP-BGP (Multiprotocol BGP): Correct. MP-BGP is the foundation for EVPN (Ethernet VPN), which is the most scalable and robust control plane for VXLAN networks. It allows the distribution of Layer 2 and Layer 3 reachability information across VTEPs (VXLAN Tunnel Endpoints). With EVPN over MP-BGP, operators can distribute MAC and IP address information, enabling seamless Layer 3 routing in VXLAN fabrics. MP-BGP also supports multiple address families, including EVPN (AFI/SAFI 25/70), making it ideal for scalable control-plane implementations in large data centers.
B. OSPF (Open Shortest Path First): Correct. While MP-BGP is the primary protocol for the overlay control plane, OSPF is often used as the underlay IGP (Interior Gateway Protocol). OSPF provides IP reachability between VTEPs, which is essential for VXLAN tunnels to function. Although it doesn’t distribute VXLAN-specific information (such as MAC addresses or VNI mappings), it plays a critical role in the overall routing architecture by enabling underlay connectivity, which VXLAN encapsulated traffic depends on.
C. IS-IS: While IS-IS is also an IGP and can be used in place of OSPF for underlay routing, it is less commonly deployed in VXLAN environments unless a specific design choice or vendor preference dictates it. It is a valid option, but not as prevalent or directly associated with VXLAN Layer 3 integration as MP-BGP and OSPF.
D. RSTP (Rapid Spanning Tree Protocol): RSTP is a Layer 2 protocol used to prevent loops in bridged Ethernet networks. It is not applicable to VXLAN Layer 3 routing and would typically be disabled in data center fabrics that use VXLAN EVPN, as loop prevention is handled by the control plane and split-horizon mechanisms.
Therefore, the best choices for integrating Layer 3 routing in a VXLAN environment are A (MP-BGP) for overlay control and B (OSPF) for underlay routing.
Question 10
In a large-scale EVPN-VXLAN data center network, which design element is essential for ensuring a highly scalable and resilient control plane?
A. Multicast flooding for VXLAN control traffic
B. L2VPN control plane extension via BGP
C. Using static routing for VXLAN tunnel endpoints
D. Single-homed connections between leaf switches
Correct Answer: B
Explanation:
As data centers grow in size and complexity, scalability and resilience of the control plane become critical for maintaining network performance, manageability, and stability. In VXLAN EVPN architectures, the control plane is responsible for advertising MAC and IP address mappings, VNI associations, and tunnel endpoint reachability.
Let’s break down the choices:
A. Multicast flooding for VXLAN control traffic: VXLAN initially relied on multicast for BUM (Broadcast, Unknown Unicast, Multicast) traffic in the flood-and-learn model. However, in EVPN deployments, control plane learning replaces multicast flooding with BGP-based MAC and IP advertisement. This eliminates the need for multicast in the control plane, significantly improving scalability and bandwidth efficiency. Using multicast for control traffic would be a legacy or non-scalable approach, not suited for large-scale deployments.
B. L2VPN control plane extension via BGP: Correct. EVPN is a BGP-based control plane solution that extends Layer 2 VPN functionality across Layer 3 VXLAN overlays. It provides efficient MAC learning, ARP suppression, and integrated Layer 2/3 routing, and it leverages MP-BGP to distribute this information across all VXLAN endpoints (VTEPs). This approach is highly scalable because it enables control-plane learning rather than relying on flooding, and it supports multi-tenancy, mobility, and network segmentation natively. This makes it the cornerstone of scalable EVPN VXLAN deployments.
C. Using static routing for VXLAN tunnel endpoints: Static routing does not scale in large environments. Every change in topology would require manual updates, which increases operational complexity and risk of misconfiguration. In scalable data centers, dynamic routing protocols like OSPF, IS-IS, or eBGP are used to handle underlay routing between VTEPs.
D. Single-homed connections between leaf switches: Single-homed designs lack resiliency. In large-scale EVPN-VXLAN designs, redundancy and multi-homing are critical to ensure high availability. EVPN natively supports multi-homing, including advanced features like ESI (Ethernet Segment Identifier) for loop prevention and load balancing. Single-homing would limit fault tolerance and is not scalable or robust.
Therefore, the correct answer is B, because EVPN's BGP-based control plane is essential to achieving the scalability and resilience expected in large-scale VXLAN deployments.
