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JNCIE-DC practice questions

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Question 1Data Center Architecture and Design

In a Juniper EVPN-VXLAN fabric, which protocol is used to advertise MAC and IP address bindings between leaf devices so that the underlay can remain a simple Layer 3 fabric?

  1. BGP with the EVPN address family Correct answer.
  2. OSPFv2 with point-to-point links
  3. LLDP with a centralized controller
  4. PIM-SM with anycast rendezvous points

Explanation

EVPN uses MP-BGP to carry MAC and IP reachability information as route types between VTEPs, which removes the need for data-plane flooding and learning across the underlay. OSPF, PIM, and LLDP serve other purposes and cannot distribute EVPN route types.

Question 2Data Center Architecture and Design

Which Junos configuration element on a QFX series switch designates the loopback interface used as the VXLAN tunnel source for a VTEP?

  1. primary-address under the interfaces lo0 hierarchy
  2. vtep-source-interface lo0.0 under the switch-options hierarchy Correct answer.
  3. router-id under the routing-options hierarchy
  4. tunnel-source under the protocols vxlan hierarchy

Explanation

The VTEP source address is defined with vtep-source-interface under switch-options, which tells the device which local address to use as the outer IP header source for VXLAN encapsulation. The router-id is used for routing protocol identity and does not itself set the tunnel source.

Question 3Data Center Architecture and Design

A design requires that all leaf devices share a single anycast gateway IP and MAC so that a virtual machine can migrate between racks without changing its default gateway. Which Juniper technology directly provides this?

  1. Multichassis Link Aggregation with active-active members
  2. Virtual Router Redundancy Protocol with preemption
  3. Bidirectional Forwarding Detection with fast intervals
  4. EVPN-VXLAN distributed anycast gateway Correct answer.

Explanation

Distributed anycast gateway configures the same IP and MAC for the integrated routing and bridging interface on every leaf, so the first-hop gateway is always local and moves with the workload. VRRP and MC-LAG address redundancy but do not give every leaf an identical local gateway MAC.

Question 4Data Center Architecture and Design

In an EVPN-VXLAN fabric, what is the primary purpose of the underlay routing protocol such as EBGP or OSPF?

  1. To distribute tenant MAC addresses between leaf devices
  2. To signal multicast group membership for broadcast traffic
  3. To synchronize the anycast gateway MAC across spines
  4. To provide loopback-to-loopback reachability for VXLAN tunnels Correct answer.

Explanation

The underlay only needs to deliver IP reachability between VTEP loopbacks so that VXLAN outer headers can be routed. Tenant MAC and IP information travels in the overlay via EVPN, not in the underlay IGP.

Question 5Data Center Architecture and Design

Which EVPN route type is used to advertise a MAC address along with its associated IP address, enabling ARP and ND suppression?

  1. Type 5 IP prefix route
  2. Type 1 Ethernet auto-discovery route
  3. Type 3 inclusive multicast Ethernet tag route
  4. Type 2 MAC/IP advertisement route Correct answer.

Explanation

Type 2 routes carry the MAC and optionally the IP address of a host, which lets remote VTEPs populate proxy ARP and neighbor tables. Type 3 handles BUM replication and Type 5 handles summarized IP prefixes for routing.

Question 6Data Center Architecture and Design

A designer wants to avoid head-end replication for broadcast, unknown unicast, and multicast traffic in a large EVPN-VXLAN fabric. Which approach should be selected?

  1. Ingress replication with a static VTEP peer list
  2. Multicast underlay using PIM with a rendezvous point Correct answer.
  3. Using Type 5 routes to carry BUM traffic
  4. Flooding BUM traffic to all spines via OSPF areas

Explanation

Multicast replication uses a PIM-built distribution tree so each packet is duplicated only where the tree branches, which scales better than ingress replication in large fabrics. Ingress replication requires the ingress VTEP to send a copy to every remote VTEP individually.

Question 7Data Center Architecture and Design

Which statement describes the role of a spine device in a Juniper IP fabric using an EBGP underlay?

  1. It terminates all VXLAN tunnels and hosts tenant IRB interfaces.
  2. It acts as the designated router for all tenant VLANs.
  3. It provides high-speed transit between leaf loopbacks and does not tunnel tenant traffic. Correct answer.
  4. It performs MAC learning for every attached host.

Explanation

Spines in an IP fabric are pure transit devices that forward encapsulated packets between leaf loopbacks and typically carry no tenant state. Leaf devices are the VTEPs that encapsulate and decapsulate tenant traffic.

Question 8Data Center Architecture and Design

When configuring an EBGP underlay between leaves and spines, which setting is commonly used on leaf devices to prevent the spine's autonomous system number from appearing in the AS path of routes learned from other leaves?

  1. allowas-in on the leaf neighbor Correct answer.
  2. remove-private on the leaf neighbor
  3. local-as on the spine neighbor
  4. as-override on the spine neighbor

Explanation

With a single spine AS, a leaf would see its own AS in paths learned through the spine, so allowas-in permits those routes to be accepted. as-override is typically applied on the spine side in designs where provider-style AS replacement is used.

Question 9Data Center Architecture and Design

Which Juniper feature allows a leaf pair to be configured as a single logical multihomed endpoint in EVPN, providing all-active forwarding to a dual-attached server?

  1. Aggregated Ethernet with LACP across separate chassis
  2. VXLAN with a static ingress replication list
  3. EVPN multihoming with an Ethernet segment identifier Correct answer.
  4. Virtual Chassis Fabric with a single control plane

Explanation

EVPN multihoming uses an Ethernet segment identifier so two or more leaf devices can act as one logical endpoint and forward all-active for a dual-homed host. This avoids the need for a single control plane such as Virtual Chassis across the pair.

Question 10Data Center Architecture and Design

In a Juniper EVPN-VXLAN design, what does the VNI in the VXLAN header identify?

  1. The BGP autonomous system of the VTEP
  2. The tenant Layer 2 or Layer 3 segment within the fabric Correct answer.
  3. The outer IP destination of the tunnel
  4. The physical uplink port used for encapsulation

Explanation

The 24-bit VNI in the VXLAN header maps to a tenant bridging or routing instance, separating segments across the shared underlay. The outer IP header carries VTEP addresses, while the VNI identifies the tenant context.

Question 11Data Center Architecture and Design

A design uses EVPN Type 5 routes for Layer 3 traffic between tenants. What must be true for a leaf to route a packet into a remote VNI?

  1. The leaf must be directly connected to the destination host.
  2. The leaf must use ingress replication for all unicast traffic.
  3. The leaf must have a local IRB interface for the destination VNI with a matching VNI mapping. Correct answer.
  4. The leaf must run OSPF with the destination leaf in the same area.

Explanation

Symmetric or asymmetric IRB routing requires the ingress leaf to have a local Layer 3 interface mapped to the destination VNI so it can encapsulate the packet with the correct VNI. Reachability to the remote host comes from EVPN routes, not direct attachment.

Question 12Data Center Architecture and Design

Which Junos statement associates a VLAN with a VXLAN network identifier inside a bridging instance on a QFX switch?

  1. encapsulation vxlan under the physical port
  2. vxlan vni under the bridge domain Correct answer.
  3. vlan-id under the interface
  4. instance-type virtual-switch under the routing instance

Explanation

Within the bridge domain configuration, the vxlan vni statement binds the Layer 2 domain to a specific VNI used in the VXLAN header. The vlan-id statement only sets the local VLAN tag and does not define the VNI.

Question 13Data Center Architecture and Design

Why is a dedicated loopback address recommended as the VTEP source rather than a physical interface address?

  1. It reduces the size of the VXLAN header.
  2. It guarantees the tunnel remains up if a single uplink fails. Correct answer.
  3. It eliminates the need for an underlay routing protocol.
  4. It allows the VNI to be reused across tenants.

Explanation

A loopback is reachable through any available path, so the VTEP source stays valid as long as any underlay path exists, improving resiliency. Physical interface addresses would change or fail when that specific link goes down.

Question 14Data Center Architecture and Design

Which design consideration favors a Layer 3 IP fabric over a large Layer 2 domain for the data center underlay?

  1. It removes the need for any overlay technology.
  2. It eliminates the requirement for loopback addresses.
  3. It allows a single VLAN to span every rack without configuration.
  4. It limits broadcast domains and provides multipath forwarding with predictable convergence. Correct answer.

Explanation

A Layer 3 fabric confines broadcast domains to the leaves and uses equal-cost multipath for resilient forwarding with fast convergence. The overlay still provides Layer 2 semantics where needed, and loopbacks remain essential for VTEP addressing.

Question 15Data Center Architecture and Design

What is the purpose of ARP and ND suppression on a Juniper EVPN-VXLAN leaf?

  1. To answer ARP and neighbor solicitations locally from EVPN-learned bindings instead of flooding them Correct answer.
  2. To elect a single designated VTEP for each subnet
  3. To encrypt tenant ARP traffic across the underlay
  4. To replace BGP with a static neighbor table

Explanation

With suppression enabled, the leaf answers ARP and ND requests using MAC/IP bindings learned through EVPN Type 2 routes, avoiding flooding to all VTEPs. This reduces BUM traffic and improves scale in large fabrics.

Question 16Data Center Architecture and Design

In a Juniper EVPN-VXLAN fabric, which interface type is used as the Layer 3 gateway for a tenant VLAN and is mapped to a VNI?

  1. A tunnel interface with a GRE encapsulation
  2. An integrated routing and bridging interface Correct answer.
  3. A physical access port in trunk mode
  4. A loopback interface with a /32 mask

Explanation

The IRB interface holds the anycast gateway address and is associated with the Layer 2 bridging domain and its VNI, enabling routing into and out of the segment. Loopbacks serve underlay and VTEP roles rather than tenant gateways.

Question 17Data Center Architecture and Design

A network architect wants to summarize tenant routes between EVPN domains. Which EVPN route type supports advertising IP prefixes rather than individual host routes?

  1. Type 3 inclusive multicast Ethernet tag route
  2. Type 2 MAC/IP advertisement route
  3. Type 5 IP prefix route Correct answer.
  4. Type 4 Ethernet segment route

Explanation

Type 5 routes advertise IP prefixes and can be used for route summarization and for routing between EVPN domains. Type 2 routes carry host MAC/IP bindings and are not suited to prefix summarization.

Question 18Data Center Architecture and Design

What does the designated forwarder election accomplish in an EVPN multihomed Ethernet segment?

  1. It selects which PE handles BUM traffic for the segment to prevent duplicate delivery. Correct answer.
  2. It selects the VTEP that owns the anycast gateway MAC.
  3. It elects the BGP route reflector for the fabric.
  4. It chooses the underlay path with the lowest IGP metric.

Explanation

For a multihomed segment, the designated forwarder is the PE responsible for forwarding BUM traffic into that segment, preventing duplicates from reaching the host. All-active unicast forwarding can still use all attached PEs.

Question 19Data Center Architecture and Design

Which Juniper routing instance type is used to create a tenant Layer 2 domain that is extended over VXLAN in an EVPN-VXLAN fabric?

  1. instance-type vrf with a route distinguisher
  2. instance-type virtual-switch Correct answer.
  3. instance-type virtual-router
  4. instance-type forwarding

Explanation

A virtual-switch instance provides the bridging domain that holds VLANs and their VNI mappings for Layer 2 extension. A VRF instance provides Layer 3 routing separation and is used alongside bridging for routed tenants.

Question 20Data Center Architecture and Design

Why do many EVPN-VXLAN designs use BGP route reflectors on the spines?

  1. To terminate multihomed Ethernet segments
  2. To provide anycast gateway services for tenant subnets
  3. To perform VXLAN encapsulation on behalf of the leaves
  4. To reduce the number of full-mesh BGP sessions required between leaf VTEPs Correct answer.

Explanation

Route reflectors allow leaves to peer with spines rather than with every other leaf, scaling the overlay control plane. The spines reflect EVPN routes but do not encapsulate tenant traffic or host tenant gateways.

Question 21Data Center Architecture and Design

Which statement about VXLAN encapsulation in a Juniper EVPN-VXLAN fabric is accurate?

  1. The original Layer 3 packet is carried inside an IP-in-IP tunnel with no UDP header.
  2. The original Layer 2 frame is carried inside a TCP segment on port 179.
  3. The original Layer 2 frame is carried inside a GRE packet with protocol 47.
  4. The original Layer 2 frame is carried inside a UDP packet with destination port 4789. Correct answer.

Explanation

VXLAN encapsulates the original frame in a UDP datagram with destination port 4789 by default, adding outer IP and Ethernet headers. This allows the encapsulated frame to traverse a routed underlay between VTEPs.

Question 22Data Center Architecture and Design

A design requires that a server dual-homed to two leaves can use both links simultaneously for traffic. Which EVPN multihoming mode provides this?

  1. Standby mode with static MAC pinning to one PE
  2. Single-active mode with one designated forwarder
  3. All-active mode with per-flow load balancing across the PEs Correct answer.
  4. Active-standby mode with VRRP master election

Explanation

All-active multihoming lets both attached PEs forward unicast traffic for the host, with the Ethernet segment identifier enabling per-flow load balancing. Single-active mode leaves one link unused except during failover.

Question 23Data Center Architecture and Design

Which factor most directly determines how many MAC addresses a leaf VTEP must store in a large EVPN-VXLAN fabric?

  1. The number of OSPF areas configured in the underlay
  2. The number of local and remote hosts whose MAC/IP bindings are learned through EVPN Correct answer.
  3. The number of physical uplinks on the spine devices
  4. The number of route reflectors deployed in the fabric

Explanation

Each leaf maintains MAC and IP bindings for hosts it learns locally and for remote hosts advertised by other VTEPs, so fabric-wide host count drives table size. Uplink count, OSPF areas, and reflector count affect control-plane topology rather than host table scale.

Question 24Data Center Architecture and Design

What is the function of a route distinguisher in an EVPN-VXLAN Layer 3 VRF design?

  1. It defines the VNI used in the VXLAN header for the tenant.
  2. It identifies the physical Ethernet segment for multihoming.
  3. It sets the anycast gateway MAC address for the subnet.
  4. It makes otherwise identical tenant prefixes unique in BGP so overlapping addresses can coexist. Correct answer.

Explanation

The route distinguisher is prepended to tenant prefixes to create unique VPN routes, allowing different tenants to use the same IP subnets. The VNI and anycast MAC are configured separately from the route distinguisher.

Question 25Data Center Architecture and Design

Which Juniper feature allows a leaf to advertise a summary route for a tenant subnet into EVPN while still maintaining host-level Type 2 entries for local hosts?

  1. Type 4 Ethernet segment routes used for summarization
  2. Type 5 IP prefix routes used alongside Type 2 host routes Correct answer.
  3. Type 3 inclusive multicast routes used for routing
  4. Type 1 Ethernet auto-discovery routes used for prefix aggregation

Explanation

Type 5 routes can advertise summarized prefixes for routing between domains, while Type 2 routes continue to carry individual host MAC/IP bindings for local traffic handling. Type 3 and Type 4 routes serve BUM replication and multihoming functions.

Question 26Data Center Architecture and Design

In a Juniper EVPN-VXLAN fabric, what is the primary purpose of a Type 2 (MAC/IP advertisement) route?

  1. It distributes MAC addresses and optionally associated IP addresses learned from local interfaces Correct answer.
  2. It signals the VTEP tunnel endpoints that participate in the underlay overlay
  3. It carries the Ethernet segment identifier used for multihoming designated forwarder election
  4. It advertises tenant IP prefixes for Layer 3 routing between VRFs

Explanation

A Type 2 route is the EVPN MAC/IP advertisement route, used to distribute MAC addresses learned locally on a leaf so remote VTEPs can populate their bridging tables and forward frames without flooding. It can optionally carry an IP address, which also enables ARP and ND suppression and host route distribution. This is distinct from Type 5, which advertises IP prefixes for Layer 3 routing.

Question 27Data Center Architecture and Design

A design team is choosing between an aggregated Ethernet bundle and EVPN multihoming for dual-homing servers to a leaf pair. Which statement correctly captures a key design difference?

  1. Aggregated Ethernet supports active-active server links across two independent leaves without any special configuration
  2. Aggregated Ethernet requires the two leaves to be a single logical switch with a shared control plane
  3. EVPN multihoming requires the server to run BGP to signal its Ethernet segment membership
  4. EVPN multihoming uses an all-active Ethernet segment so the server can forward over both links without LACP to a single logical device Correct answer.

Explanation

EVPN multihoming defines an Ethernet segment spanning multiple leaves, and in all-active mode the server can use both links simultaneously while designated forwarder election prevents duplicate BUM delivery. Aggregated Ethernet across two independent leaves requires them to appear as one logical device (for example with MC-LAG), which couples their control planes. EVPN multihoming avoids that coupling and does not require the server to run BGP.

Question 28Data Center Architecture and Design

When sizing the MAC table of a leaf VTEP in a large EVPN-VXLAN fabric, which design choice most directly reduces the number of remote MAC addresses the leaf must learn?

  1. Enabling ARP and ND suppression on all IRB interfaces
  2. Increasing the VXLAN UDP source port range on the tunnel interfaces
  3. Deploying Layer 3 gateways at the leaf and routing between subnets rather than extending large Layer 2 domains Correct answer.
  4. Using a dedicated loopback as the VTEP source address

Explanation

Routing between subnets at the leaf keeps broadcast domains small, so each VTEP only needs MAC addresses for hosts in its local subnets rather than for every host in a large stretched Layer 2 domain. ARP and ND suppression reduces ARP flooding but does not eliminate remote MAC learning for bridged traffic. VTEP loopback addressing and UDP source port ranges affect reachability and load balancing, not MAC scale.

Question 29Data Center Architecture and Design

In a Juniper EVPN-VXLAN design, which statement describes the role of the route distinguisher in a Layer 3 VRF context?

  1. It uniquely identifies the tenant VRF's routes so identical prefixes from different VRFs remain distinct in BGP Correct answer.
  2. It selects which Ethernet segment the designated forwarder uses for BUM traffic
  3. It identifies the VXLAN network identifier used to encapsulate tenant traffic
  4. It determines the underlay next hop used to reach a remote VTEP

Explanation

The route distinguisher is prepended to routes from a VRF so that overlapping prefixes from different tenants remain unique in the EVPN BGP table. Route targets then control which VRFs import those routes. The VNI is a separate value carried in the VXLAN header and EVPN attributes, and the underlay next hop comes from the VTEP loopback address.

Question 30Data Center Architecture and Design

An architect must connect two separate EVPN-VXLAN fabrics across a WAN while keeping each fabric's underlay independent. Traffic between tenants must be routed, and the design should avoid stretching Layer 2 between sites. Which approach best fits these requirements?

  1. Extend the same VLAN and VNI across both fabrics over a Layer 2 WAN handoff
  2. Flood unknown unicast between fabrics so hosts can resolve each other via ARP
  3. Use EVPN multihoming with a shared Ethernet segment spanning both sites
  4. Use EVPN Type 5 IP prefix routes to route between fabrics over a Layer 3 interconnect Correct answer.

Explanation

Advertising tenant subnets as EVPN Type 5 IP prefix routes allows inter-site traffic to be routed at Layer 3 without extending broadcast domains, keeping each fabric's underlay independent. Stretching VLANs and VNIs over a Layer 2 WAN handoff reintroduces large failure domains and BUM flooding across the WAN. EVPN multihoming is designed for local Ethernet segments, not for linking geographically separate fabrics.

Question 31EVPN-VXLAN Fabric Configuration

In an EVPN-VXLAN fabric using Junos, which route type carries the MAC address and IP address of a locally attached host so that remote leaf devices can populate their ARP/ND tables?

  1. Type 3 route
  2. Type 2 route Correct answer.
  3. Type 5 route
  4. Type 1 route

Explanation

Type 2 (MAC/IP advertisement) routes carry the host MAC, optional IP, and the VTEP next hop, enabling remote leaves to learn host reachability and to build proxy ARP/ND entries. Type 3 handles flooding, Type 5 handles prefix routes, and Type 1 handles multihoming.

Question 32EVPN-VXLAN Fabric Configuration

Which EVPN route type must be exchanged between VTEPs to establish the underlay-independent multicast or ingress-replication flooding tree for a VXLAN VNI?

  1. Type 5 route
  2. Type 4 route
  3. Type 2 route
  4. Type 3 route Correct answer.

Explanation

The Type 3 inclusive multicast Ethernet tag route advertises the VTEP's participation in a VNI and its originating IP, which peers use to build the flooding list for BUM traffic. Without Type 3 routes, unknown unicast, broadcast, and multicast frames cannot be delivered to remote VTEPs.

Question 33EVPN-VXLAN Fabric Configuration

On a Junos leaf device, which configuration statement associates a VLAN with a VXLAN network identifier inside the EVPN-VXLAN routing instance?

  1. vni 10010 under the bridge domain
  2. vxlan vni 10010 under the VLAN Correct answer.
  3. encapsulate vxlan vni 10010 under protocols evpn
  4. vxlan-id 10010 under the interface

Explanation

In Junos EVPN-VXLAN configuration the VNI is mapped to a VLAN using the vxlan vni statement under the VLAN definition within the routing instance. The VLAN-to-VNI mapping determines which traffic is encapsulated and which VNI appears in the EVPN route attributes.

Question 34EVPN-VXLAN Fabric Configuration

Which Junos statement enables a routing instance to act as a VTEP and originate EVPN-VXLAN encapsulation for its VLANs?

  1. set routing-instances DC forwarding-options vxlan
  2. set routing-instances DC protocols vxlan enable
  3. set routing-instances DC protocols evpn encapsulation vxlan Correct answer.
  4. set routing-instances DC bridge-domains vxlan

Explanation

The EVPN-VXLAN data plane is enabled by setting protocols evpn encapsulation vxlan within the routing instance. This causes the device to source VXLAN-encapsulated traffic and to signal EVPN routes for the configured VNIs.

Question 35EVPN-VXLAN Fabric Configuration

A design team wants each leaf to have a single underlay IP address used both for VXLAN encapsulation source and for EVPN peering. Which interface type best satisfies this requirement on Junos?

  1. A routed VLAN interface on the spine
  2. A physical uplink interface with an IRB address
  3. A management interface (fxp0/em0)
  4. A loopback interface (lo0) with a /32 address Correct answer.

Explanation

Using a stable loopback /32 as the VTEP source and BGP router-id decouples the tunnel endpoints from physical link state, so any spine or uplink failure does not change the VTEP address. Physical and management interfaces are unsuitable because their reachability or addresses can change.

Question 36EVPN-VXLAN Fabric Configuration

Which VXLAN component provides the 24-bit identifier that scopes a Layer 2 segment across the fabric?

  1. The VXLAN Network Identifier (VNI) Correct answer.
  2. The EVPN route distinguisher
  3. The BGP extended community
  4. The Ethernet segment identifier

Explanation

The VNI is a 24-bit value in the VXLAN header that identifies the Layer 2 segment, allowing up to roughly 16 million segments. Route distinguishers and extended communities are BGP attributes, and the ESI identifies a multihomed segment, not a Layer 2 domain.

Question 37EVPN-VXLAN Fabric Configuration

In an EVPN-VXLAN fabric, which mechanism prevents a remote leaf from flooding an unknown unicast frame to every VTEP once MAC learning has converged?

  1. The remote leaf sends the frame to the border leaf for resolution
  2. The remote leaf forwards the frame to the spine for MAC lookup
  3. The remote leaf floods the frame to all VTEPs in the VNI permanently
  4. The remote leaf drops the frame because no Type 2 route exists for the destination MAC Correct answer.

Explanation

When no Type 2 route matches the destination MAC, the leaf treats the frame as unknown unicast and drops it rather than flooding, which is the default behavior once EVPN MAC learning is in effect. This suppresses unnecessary BUM replication for unicast traffic and is a key scaling benefit of EVPN.

Question 38EVPN-VXLAN Fabric Configuration

Which route target configuration ensures that EVPN routes for VNI 20010 are imported only by leaf devices participating in that VNI?

  1. A matching vrf-target on the routing instance that corresponds to the VNI's tenant Correct answer.
  2. A route target derived from the underlay BGP AS number
  3. A unique route distinguisher per leaf with no route target
  4. A single shared route target applied to every routing instance in the fabric

Explanation

Route targets control EVPN route import and export, so each tenant or VNI must use a matching vrf-target to import only the routes it needs. Using a shared route target across all instances would leak routes between tenants, and the route distinguisher alone does not control import.

Question 39EVPN-VXLAN Fabric Configuration

A leaf is configured with an anycast IRB address shared with peer leaves for the same VLAN. Which behavior allows hosts on other leaves to reach that gateway address without a dedicated first-hop protocol?

  1. The anycast MAC and IP are advertised in Type 2 routes so all leaves can answer ARP/ND locally Correct answer.
  2. The border leaf answers all ARP requests for the subnet
  3. Each leaf uses a unique MAC and relies on the spine to proxy ARP
  4. The anycast address is resolved only via the underlay routing protocol

Explanation

Distributed anycast gateway uses a shared anycast MAC and IP advertised through EVPN Type 2 routes, so every leaf can respond to ARP/ND for the gateway locally and forward traffic optimally. This avoids tromboning traffic to a single gateway and removes the need for VRRP or similar first-hop redundancy protocols.

Question 40EVPN-VXLAN Fabric Configuration

Which Junos feature allows a leaf to suppress ARP requests from being flooded across the VXLAN overlay by answering on behalf of remote hosts?

  1. Static ARP entries configured on each leaf
  2. DHCP snooping on the border leaf
  3. Proxy ARP/ND driven by EVPN Type 2 host routes Correct answer.
  4. Gratuitous ARP suppression on the spine

Explanation

When a leaf has learned remote host IP-to-MAC bindings through EVPN Type 2 routes, it can answer ARP/ND requests locally for those hosts, a function often called ARP/ND suppression. This reduces BUM traffic in the overlay and improves convergence.

Question 41EVPN-VXLAN Fabric Configuration

In a Junos EVPN-VXLAN configuration, what is the effect of setting the same Ethernet segment identifier on two leaf devices attached to the same dual-homed server?

  1. The leaves load-balance BUM traffic by flooding to both simultaneously without DF election
  2. The leaves disable EVPN Type 2 advertisement for that segment
  3. The leaves form a single VTEP with a shared loopback address
  4. The leaves form a multihomed Ethernet segment and elect a designated forwarder per VLAN Correct answer.

Explanation

A shared ESI identifies the dual-homed segment, enabling DF election so only one leaf forwards BUM traffic for a given VLAN while both can advertise the host. This provides active-active multihoming with loop prevention and fast failover.

Question 42EVPN-VXLAN Fabric Configuration

Which statement about the underlay in a Junos EVPN-VXLAN fabric is correct when using an EBGP underlay between leaves and spines?

  1. Leaves and spines peer over loopbacks with multihop EBGP and advertise only loopback and p2p prefixes Correct answer.
  2. Leaves peer with each other directly over the overlay VNI
  3. The underlay must use OSPF because EBGP cannot carry loopback routes
  4. Spines must run EVPN with the leaves to forward VXLAN traffic

Explanation

A common design uses EBGP between leaves and spines over loopback addresses with multihop, advertising only loopbacks and point-to-point link prefixes to keep the underlay lean. Spines remain pure IP forwarders and do not need EVPN, which keeps the overlay control plane at the leaves.

Question 43EVPN-VXLAN Fabric Configuration

A design requires inter-subnet routing within the EVPN-VXLAN fabric without sending traffic to an external router. Which EVPN mechanism enables this?

  1. Type 3 routes with a shared VNI across all subnets
  2. Symmetric IRB using Type 5 routes and per-VNI VRF route targets Correct answer.
  3. Type 1 routes with ESI-based forwarding
  4. Type 4 routes with DF election

Explanation

Symmetric IRB routes traffic between VNIs on the leaf using Type 5 IP prefix routes and per-VRF route targets, keeping the traffic distributed and avoiding a central gateway. Type 3, Type 1, and Type 4 routes serve flooding, multihoming, and DF election respectively, not inter-subnet routing.

Question 44EVPN-VXLAN Fabric Configuration

When configuring a Junos leaf for EVPN-VXLAN, which BGP configuration is required to carry EVPN routes to the route reflector?

  1. family inet unicast under the BGP group
  2. family evpn signaling under the BGP group Correct answer.
  3. family l2vpn signaling under the BGP group
  4. family inet-vpn unicast under the BGP group

Explanation

EVPN Network Layer Reachability Information is exchanged using the family evpn signaling address family in BGP. Without it, the session comes up but EVPN routes such as Type 2 and Type 3 are not advertised or received.

Question 45EVPN-VXLAN Fabric Configuration

Which value in a Type 2 EVPN route allows a leaf to associate a remote host MAC with the correct VNI on the local device?

  1. The VXLAN Network Identifier carried in the route's extended community or label field Correct answer.
  2. The OSPF metric of the underlay route
  3. The BGP local preference
  4. The route distinguisher of the originating leaf

Explanation

The Type 2 route carries the VNI, typically encoded in the VXLAN label or an extended community, so the receiving leaf maps the remote MAC/IP to the correct local VLAN and VNI. Local preference and underlay metrics affect path selection but not segment association.

Question 46EVPN-VXLAN Fabric Configuration

A Junos leaf shows EVPN Type 2 routes received but hosts on a remote leaf cannot be reached. Which verification step most directly confirms whether the local VLAN is bound to the expected VNI?

  1. Run show bgp summary and check the session state
  2. Run show route table inet.0 and check the loopback prefix
  3. Run show arp and check the gateway MAC
  4. Run show evpn vni detail and check the VLAN-to-VNI association Correct answer.

Explanation

The show evpn vni detail command displays each VNI, its associated VLAN, and VTEP information, directly confirming whether the local mapping matches the remote advertisement. Checking the underlay route table or BGP summary verifies transport but not the tenant binding.

Question 47EVPN-VXLAN Fabric Configuration

Which Junos command displays the EVPN database entries that map MAC addresses to VTEPs and VNIs on a leaf?

  1. show route table evpn.0
  2. show vxlan tunnels
  3. show evpn database Correct answer.
  4. show ethernet-switching table

Explanation

The show evpn database command lists learned MAC and IP entries along with their VTEP, VNI, and origin, making it the primary tool for verifying overlay MAC learning. The Ethernet switching table shows local bridging, and the evpn.0 table shows routes rather than the MAC database.

Question 48EVPN-VXLAN Fabric Configuration

In a Junos EVPN-VXLAN fabric, a Type 5 route is received for a remote subnet. Which configuration element on the local leaf determines whether that prefix is installed into the tenant VRF?

  1. The underlay BGP local preference
  2. The VTEP loopback address
  3. The ESI value of the remote segment
  4. A matching vrf-target on the tenant routing instance Correct answer.

Explanation

Type 5 routes are imported into a VRF only when their route target matches the vrf-target configured on that routing instance. Local preference affects best-path selection but not import eligibility, and the VTEP loopback and ESI are unrelated to VRF import policy.

Question 49EVPN-VXLAN Fabric Configuration

A network engineer wants to prevent a leaf from advertising Type 2 routes for a VLAN that should remain local-only. Which approach is most appropriate in Junos?

  1. Set a higher local preference on the Type 2 routes
  2. Do not map the VLAN to a VNI and exclude it from the EVPN routing instance Correct answer.
  3. Disable the Type 3 route for that VNI
  4. Change the route distinguisher for that VLAN

Explanation

A VLAN that is not mapped to a VNI and not part of the EVPN routing instance has no overlay presence, so no Type 2 routes are generated for it. Adjusting local preference or the route distinguisher does not stop advertisement, and disabling Type 3 would break flooding for other VLANs sharing the VNI.

Question 50EVPN-VXLAN Fabric Configuration

During a maintenance window, a leaf's loopback address is changed. Which two EVPN consequences should the engineer expect? (Choose the single best answer.)

  1. The underlay BGP session resets but EVPN routes remain unchanged
  2. Existing Type 2 routes are automatically rewritten without any reconvergence
  3. The VNI mappings on remote leaves are invalidated permanently
  4. New Type 3 and Type 2 routes are advertised with the new VTEP address, and remote leaves must relearn the host bindings Correct answer.

Explanation

The loopback is the VTEP source address carried in EVPN routes, so changing it causes the leaf to re-originate Type 2 and Type 3 routes with the new next hop. Remote leaves withdraw the old bindings and relearn them against the new VTEP, causing a brief reconvergence.