Juniper JN0-683 Online Practice Questions and Exam Preparation

Juniper JN0-683 Online Questions & Answers

• Question 51:

  Why is a designated forwarder required in a multihomed CE-to-PE VXLAN environmentusing EVPN signalling?

  A. The designated forwarder is required to prevent packets from looping between the PEs.
  B. The designated forwarder is required to prevent flooding of MAC addresses to multihomed hosts.
  C. The designated forwarder is required to prevent a traffic storm from being received on multihomed hosts.
  D. The designated forwarder is required to prevent duplicate packets from being received on multihomed hosts.
  D. The designated forwarder is required to prevent duplicate packets from being received on multihomed hosts.

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  Explanation

  Understanding Multihomed CE-to-PE VXLAN Environment:

  In a VXLAN environment using EVPN signaling, multiple PEs (Provider Edge devices) can be connected to the same CE (Customer Edge device). This setup is referred to as multihoming, where a CE device has multiple connections to the

  network to ensure redundancy and load balancing.

  Role of the Designated Forwarder:

  The designated forwarder (DF) is a mechanism used in EVPN to manage the forwarding of broadcast, unknown unicast, and multicast (BUM) traffic in a multihomed environment. The DF is selected to ensure that only one of the PEs forwards

  this type of traffic to the CE, preventing loops and unnecessary duplicate packets.

  Avoiding Duplicate Packets:

  Without a designated forwarder, all PEs connected to a multihomed CE could potentially forward the same packet to the CE, resulting in duplicate packets. This duplication can cause issues with packet processing on the CE, leading to

  inefficiencies and potential network problems.

  Conclusion:

  Option D:Correct--The designated forwarder is essential to prevent duplicate packets from being received on multihomed hosts, ensuring that only one PE forwards BUM traffic to the CE.

• Question 52:

  You are using E8GP peering in an underlay IP fabric. Which two statements are correct in this scenario? (Choose two.)

  A. EBGP peering requires an IGP protocol tor adjacency establishment.
  B. EBGP peering does not require an IGP protocol tor adjacency establishment.
  C. Every leaf node has one peering session to every spine node.
  D. Every leaf node has a peering session to every other leaf node.
  B. EBGP peering does not require an IGP protocol tor adjacency establishment.
  C. Every leaf node has one peering session to every spine node.

  ---

  Explanation

  Understanding EBGP in an IP Fabric:

  EBGP (External Border Gateway Protocol) is commonly used in IP fabrics to establish peering between routers, such as leaf and spine nodes, without relying on an Interior Gateway Protocol (IGP) like OSPF or IS-IS.

  IGP Requirement for EBGP:

  Option B:EBGP peering does not require an IGP for adjacency establishment. This is because EBGP peers are typically directly connected, and BGP establishes its own sessions without needing an underlying IGP.

  Leaf-to-Spine Peering:

  Option C:In a typical IP fabric, each leaf node establishes an EBGP session with every spine node. This ensures full connectivity between leaves and spines, facilitating efficient routing and forwarding within the fabric.

  Conclusion:

  Option B:Correct--EBGP does not require an IGP for establishing peering sessions.

  Option C:Correct--Each leaf node peers with every spine node, which is a standard practice in IP fabrics to ensure connectivity and redundancy.

• Question 53:

  You are asked to implement VXLAN group-based policies (GBPs) in your data center. Which two statements are correct in (his scenario? (Choose two.)

  A. VXLAN GBP uses scalable group tags thatmust be configured statically on each switch and activated through 802.1X.
  B. VXLAN GBP uses scalable group tags that may be configured on a RADIUS server and pushed to the switch through 802.1X.
  C. VXLAN GBP ensures consistent application of security group policies throughout the network.
  D. VXLAN GBP ensures consistent application of BGP groups throughout the network.
  B. VXLAN GBP uses scalable group tags that may be configured on a RADIUS server and pushed to the switch through 802.1X.
  C. VXLAN GBP ensures consistent application of security group policies throughout the network.

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  Explanation

  VXLAN Group-Based Policies (GBP):

  VXLAN Group-Based Policies are used to apply security policies consistently across the network. These policies are often tied to user or device identities rather than static IP addresses, which allows for more dynamic and scalable security

  management.

  Scalable Group Tags via RADIUS and 802.1X:

  Option B:VXLAN GBP can use scalable group tags configured on a RADIUS server, which are then pushed to network devices through 802.1X. This allows for centralized and automated policy application based on user or device identity.

  Consistent Security Policy Application:

  Option C:GBP ensures that security policies are consistently applied across the network, regardless of where a user or device connects. This consistency is crucial in environments where security policies must follow the user or device.

  Conclusion:

  Option B:Correct--Group tags can be configured on a RADIUS server and pushed via 802.1X, enabling centralized policy management.

  Option C:Correct--GBP ensures consistent application of security policies, which is essential for maintaining security across a dynamic network environment.

• Question 54:

  Exhibit.

  

  You have implemented an EVPN-VXLAN data center. Device served must be able to communicate with device server2. Referring to the exhibit, which two statements are correct? (Choose two.)

  A. An IRB interface must be configured on spinel and spine2.
  B. Traffic from server1 to server2 will transit a VXLAN tunnel to spinel or spine2. then a VXLAN tunnel from spinel or spine2 to Ieaf2.
  C. An IRB Interface must be configured on leaf1 and Ieaf2.
  D. Traffic from server! to server2 will transit the VXLAN tunnel between leaf1 and Ieaf2.
  C. An IRB Interface must be configured on leaf1 and Ieaf2.
  D. Traffic from server! to server2 will transit the VXLAN tunnel between leaf1 and Ieaf2.

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  Explanation

  Understanding the Exhibit Setup:

  The network diagram shows an EVPN-VXLAN setup, a common design for modern data centers enabling Layer 2 and Layer 3 services over an IP fabric.

  Leaf1 and Leaf2 are the leaf switches connected to Server1 and Server2, respectively, with each server in a different subnet (172.16.1.0/24 and 172.16.2.0/24).

  Spine1 and Spine2 are part of the IP fabric, interconnecting the leaf switches.

  EVPN-VXLAN Basics:

  EVPN (Ethernet VPN) provides Layer 2 and Layer 3 VPN services using MP-BGP.

  VXLAN (Virtual Extensible LAN) encapsulates Layer 2 frames into Layer 3 packets for transmission across an IP network.

  VTEP (VXLAN Tunnel Endpoint) interfaces on leaf devices handle VXLAN encapsulation and decapsulation.

  Integrated Routing and Bridging (IRB):

  IRB interfaces are required on leaf1 and leaf2 (where the endpoints are directly connected) to route between different subnets (in this case, between 172.16.1.0/24 and 172.16.2.0/24).

  The IRB interfaces provide the necessary L3 gateway functions for inter-subnet communication.

  Traffic Flow Analysis:

  Traffic from Server1 (172.16.1.1) destined for Server2 (172.16.2.1) must traverse from leaf1 to leaf2. The traffic will be VXLAN encapsulated on leaf1, sent over the IP fabric, and decapsulated on leaf2. Since the communication is between different subnets, the IRB interfaces on leaf1 and leaf2 are crucial for routing the traffic correctly.

  Correct Statements:

  C. An IRB Interface must be configured on leaf1 and leaf2:This is necessary to perform the inter-subnet routing for traffic between Server1 and Server2.

  D. Traffic from server1 to server2 will transit the VXLAN tunnel between leaf1 and leaf2:

  This describes the correct VXLAN operation where the traffic is encapsulated by leaf1 and decapsulated by leaf2. Data Center

  References:

  In EVPN-VXLAN architectures, the leaf switches often handle both Layer 2 switching and Layer 3 routing via IRB interfaces. This allows for efficient routing within the data center fabric without the need to involve the spine switches for every

  routing decision.

  The described traffic flow aligns with standard EVPN-VXLAN designs, where direct VXLAN tunnels between leaf switches enable seamless and scalable communication across a data center network.

• Question 55:

  Your organization is implementing EVPN-VXLAN and requires multiple overlapping VLAN-IDs. You decide to use a routing-instance type mac-vrf to satisfy this request.

  Which two statements are correct in this scenario? (Choose two.)

  A. Host-facing interfaces must be configured using a service-provider style configuration.
  B. Host-facing interfaces must be configured using enterprise-style configuration.
  C. Spine-facing interfaces must be configured using an enterprise-styleconfiguration.
  D. The routing-instance service type can be VLAN-based.
  A. Host-facing interfaces must be configured using a service-provider style configuration.
  D. The routing-instance service type can be VLAN-based.

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  Explanation

  Understanding the Scenario:

  EVPN-VXLAN deployments often involve scenarios where multiple tenants or applications require overlapping VLAN IDs, which can be managed using the mac-vrf routing instance type. This allows you to segregate traffic within the same

  VLAN ID across different tenants.

  Host-facing Interface Configuration:

  A. Host-facing interfaces must be configured using a service-provider style configuration:

  This is correct. In mac-vrf configurations, host-facing interfaces (those connecting end devices) typically follow a service-provider style configuration, where each customer or tenant's traffic is isolated even if overlapping VLAN IDs are used.

  B. Host-facing interfaces must be configured using enterprise-style configuration:This is incorrect for mac-vrf instances because enterprise-style configurations are more common in simpler, less segmented networks.

  Routing Instance Service Type:

  D. The routing-instance service type can be VLAN-based:This is correct. The service type in mac-vrf can indeed be VLAN-based, which is particularly useful in scenarios where VLAN ID overlap is needed between different tenants or

  services.

  Data Center

  References:

  The mac-vrf instance type is powerful for handling complex multi-tenant environments in EVPN- VXLAN, especially when dealing with overlapping VLAN IDs across different segments of the network.

• Question 56:

  Exhibit.

  

  Referring to the exhibit, which statement Is true?

  A. A PBB-EVPN architecture is being used.
  B. An ERB architecture is being used.
  C. An OTT architecture is being used.
  D. A CRB architecture is being used.
  B. An ERB architecture is being used.

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  Explanation

  Understanding Network Architectures:

  ERB (Edge Routed Bridging) architecture involves routing at the network's edge (leaf nodes), while traffic between leaf nodes is switched. This is commonly used in VXLAN-EVPN setups.

  Analysis of the Exhibit:

  The exhibit shows configurations related to routing instances, VXLAN, and VLANs, with VNIs being used for each VLAN. This setup is characteristic of an ERB architecture where each leaf device handles Layer 3 routing for its connected

  devices.

  Conclusion:

  Option B:Correct--The configuration shown corresponds to an ERB architecture where routing occurs at the network's edge (leaf devices).

• Question 57:

  Which statement is correct about a collapsed fabric EVPN-VXLAN architecture?

  A. Fully meshed back-to-back links are needed between the spine devices.
  B. It supports multiple vendors in the fabric as long as all the spine devices are Juniper devices deployed with L2 VTEPs
  C. Using Virtual Chassis at the leaf layer increases resiliency.
  D. Border gateway functions occur on border leaf devices.
  D. Border gateway functions occur on border leaf devices.

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  Explanation

  Collapsed Fabric Architecture:

  A collapsed fabric refers to a simplified architecture where the spine and leaf roles are combined, often reducing the number of devices and links required.

  In this architecture, the spine typically handles core switching, while leaf switches handle both access and distribution roles.

  Understanding Border Gateway Functionality:

  Border gateway functions include connecting the data center to external networks or other data centers.

  In a collapsed fabric, these functions are usually handled at the leaf level, particularly on border leaf devices that manage the ingress and egress of traffic to and from the data center fabric.

  Correct Statement:

  D. Border gateway functions occur on border leaf devices:This is accurate in collapsed fabric architectures, where the border leaf devices take on the role of managing external connections and handling routes to other data centers or the

  internet.

  Data Center

  References:

  The collapsed fabric model is advantageous in smaller deployments or scenarios where simplicity and cost-effectiveness are prioritized. It reduces complexity by consolidating functions into fewer devices, and the border leaf handles the

  critical task of interfacing with external networks.

  In conclusion, border gateway functions are effectively managed at the leaf layer in collapsed fabric architectures, ensuring that the data center can communicate with external networks seamlessly.

• Question 58:

  Which two statements are true about a pure IP fabric? (Choose two.)

  A. Devices in an IP fabric function as Layer 3 routers.
  B. An IP fabric supports Layer 2 VLANs.
  C. Devices in an IP fabric must be connected to a fabric controller.
  D. An IP fabric does not support Layer 2 protocols.
  A. Devices in an IP fabric function as Layer 3 routers.
  D. An IP fabric does not support Layer 2 protocols.

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  Explanation

  Understanding Pure IP Fabric:

  A pure IP fabric is a network design where all devices operate at Layer 3, meaning that each device in the fabric is a router that makes forwarding decisions based on IP addresses.

  Layer 2 Support:

  In a pure IP fabric, traditional Layer 2 protocols such as Spanning Tree Protocol (STP) or VLANs are not supported. Instead, the network relies entirely on Layer 3 routing protocols to manage traffic between devices.

  Routing Functionality:

  Since devices in an IP fabric operate as Layer 3 routers, they handle IP routing and provide network services based on IP addresses, not on MAC addresses or Layer 2 switching.

  Conclusion:

  Option A:Correct--Devices in an IP fabric function as Layer 3 routers.

  Option D:Correct--A pure IP fabric does not support traditional Layer 2 protocols, making it a purely routed environment.

• Question 59:

  Exhibit.

  

  Referring to the exhibit, why is the active source field blank for the entry that uses the 00:0c:29:e8:b7:39 MAC address?

  A. The EVPN route for this host does not have a valid next hop.
  B. The ARP lookup for this host has failed.
  C. The host for this entry is locally connected to leaf1.
  D. This entry is associated with a multicast EVPN route.
  A. The EVPN route for this host does not have a valid next hop.

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  Explanation

  In this scenario, the active source field is blank for the MAC address 00:0c:29:e8:b7:39, indicating an issue with how this MAC entry is being processed within the EVPN/VXLAN environment.

  Step-by-Step Analysis:

  Understanding the MAC Entry:

  The active source field should normally indicate the source of the route advertisement for a specific MAC address within the EVPN. If it is blank, it suggests that there is a problem with how this entry is being learned or propagated.

  Possible Issues:

  Option A:If the EVPN route for this MAC address does not have a valid next hop, the entry might exist in the MAC table, but it will not have a valid path for forwarding, leading to a blank active source.

  Option B:If the ARP lookup had failed, the entry might not even appear in the MAC table. However, the entry does exist, suggesting that ARP is not the primary issue here.

  Option C:If the host were locally connected, the active source should reflect a local interface, but the field is blank, ruling out local connection as the cause.

  Option D:Multicast EVPN routes typically do not appear in this manner in the MAC table, and this would not cause the active source to be blank.

  Conclusion:The most logical explanation is that the EVPN route for this host exists but does not have a valid next hop, leading to the absence of an active source. This is consistent with how EVPN routing tables work in a VXLAN environment,

  where the lack of a valid next hop would prevent proper route advertisement and forwarding for the specific MAC address.

• Question 60:

  Exhibit.

  

  You are deploying a VXLAN overlay with EVPN as the control plane in an ERB architecture.

  Referring to the exhibit, which three statements are correct about where the VXLAN gateways will be placed? (Choose three.)

  A. Only the spine devices will have L2 VXLAN gateways.
  B. All leaf devices will have L2 VXLAN gateways.
  C. All leaf devices will have L3 VXLAN gateways.
  D. Only the border and leaf devices will have L3 VXLAN gateways.
  E. Spine devices will have no VXLAN gateways.
  B. All leaf devices will have L2 VXLAN gateways.
  C. All leaf devices will have L3 VXLAN gateways.
  E. Spine devices will have no VXLAN gateways.

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  Explanation

  Understanding ERB Architecture:

  ERB (Edge Routed Bridging) architecture is a network design where the routing occurs at the edge (leaf devices) rather than in the spine devices. In a VXLAN overlay network with EVPN as the control plane, leaf devices typically act as both

  Layer 2 (L2) and Layer 3 (L3) VXLAN gateways.

  Placement of VXLAN Gateways:

  Option B:All leaf devices will have L2 VXLAN gateways to handle the bridging of VLAN traffic into VXLAN tunnels.

  Option C:All leaf devices will also have L3 VXLAN gateways to route traffic between different VXLAN segments (VNIs) and external networks.

  Option E:Spine devices in an ERB architecture generally do not function as VXLAN gateways. They primarily focus on forwarding traffic between leaf nodes and do not handle VXLAN encapsulation/decapsulation.

  Conclusion:

  Option B:Correct--All leaf devices will have L2 VXLAN gateways.

  Option C:Correct--All leaf devices will have L3 VXLAN gateways.

  Option E:Correct--Spine devices will not act as VXLAN gateways