JNCIP-ENT EVPN Practice Test 2 — 15 Questions

Question 1

An engineer is troubleshooting a newly configured EVPN-VXLAN multi-homed setup where the Designated Forwarder (DF) is constantly toggling between two PE routers. What is the most likely cause of this DF churn?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Mismatched Ethernet Segment Identifiers (ESIs) or unstable BGP connectivity between PEs.. DF churn typically occurs when BGP sessions or reachability between the PE routers flapping, or when the timers (such as wait-for-timer) are misconfigured, causing conflicting DF election states.

Answer

Incorrect MAC mobility sequence numbers.

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Exceeding the maximum MAC address table limit.

Answer

Using VXLAN instead of MPLS data plane encapsulation.

Question 2

Which EVPN route type is responsible for advertising MAC addresses combined with IP addresses (MAC/IP Advertisement Route)?

Accepted Answer

Route Type 2. Route Type 2 is the MAC/IP Advertisement Route, which carries a MAC address and optionally an IP address, facilitating both L2 bridging and L3 host routing.

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Route Type 3

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Route Type 4

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Route Type 1

Question 3

You are designing an EVPN network with active-active multi-homing. A host sends traffic to a multi-homed PE. The PE receives the traffic on a designated link. How does EVPN suppress unnecessary flooding across the core for unknown unicast traffic originating from a multi-homed site?

Accepted Answer

By dynamically learning MAC addresses via control-plane Type 2 routes, turning unknown unicast into known unicast.. EVPN suppresses unknown unicast flooding by performing MAC learning via control-plane advertisement (Type 2 routes) upon first contact, so subsequent traffic is unicast-forwarded rather than flooded.

Answer

By utilizing Spanning Tree Protocol to block redundant ports across the core.

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By dropping all packets with unknown destination MAC addresses at the ingress leaf.

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By enforcing ingress replication drop filters on Type 3 routes.

Question 4

You are analyzing BGP EVPN updates and observe an Extended Community attached to a Type-2 route containing a sequence number. What is the primary function of this MAC Mobility Extended Community?

Accepted Answer

It facilitates loop-free MAC movement tracking by incrementing sequence numbers when a host changes attachment PEs.. The MAC Mobility Extended Community carries a sequence number used to resolve MAC moves. If a host moves from one PE to another, the new PE advertises the MAC with an incremented sequence number, causing all other PEs to update their tables to point to the new location.

Answer

It signals the EVPN split-horizon label for BUM traffic.

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It determines the Designated Forwarder for multi-homed Ethernet segments.

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It defines the VXLAN Network Identifier (VNI) mapping for data-plane decapsulation.

Question 5

An administrator wishes to configure VXLAN data plane encapsulation on an MX Series router with an EVPN instance. Which statement under the routing-instances hierarchy defines the local VTEP source interface?

Accepted Answer

vtep-source-interface lo0.0;. In Junos OS, the VXLAN source interface is defined using the 'vtep-source-interface' statement under the EVPN routing instance or switch-options hierarchy.

Answer

encapsulation-source-interface fxp0.0;

Answer

vxlan-source-ip lo0.0;

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tunnel-source loopback 0;

Question 6

Which EVPN route type is responsible for establishing ingress replication lists for Broadcast, Unknown Unicast, and Multicast (BUM) traffic?

Accepted Answer

Route Type 3. Route Type 3 (Inclusive Multicast Ethernet Tag Route) is used to build the peer list for BUM traffic distribution using ingress replication (head-end replication).

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Route Type 5

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Route Type 4

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Route Type 1

Question 7

You are troubleshooting a scenario where an MX Series router running an EVPN-VXLAN instance receives Type-2 routes from a remote PE, but the local data plane fails to install the forwarding entries because of a mismatch in encapsulation types. Where is the encapsulation type for VXLAN defined within a Junos EVPN instance?

Accepted Answer

routing-instances <name> instance-type evpn; ... encapsulation vxlan;. In Junos OS, the encapsulation for the routing instance or switch options is defined using the 'encapsulation vxlan' statement under the routing-instance or switch-options hierarchy.

Answer

protocols bgp group <name> family evpn encapsulation vxlan

Answer

interfaces lo0.0 family vxlan

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bridge-domains vni encapsulation mpls

Question 8

An administrator configures EVPN with VXLAN encapsulation and wants to ensure that interfaces assigned to bridge domains drop frames whose source MAC address is not learned or is unauthorized. Which feature should be enabled?

Accepted Answer

MAC security / MAC limit with drop action. Configuring MAC limit or bpdu protection/port security features on access interfaces prevents unauthorized MAC learning, while EVPN sticky MAC features can lock MACs to specific interfaces.

Answer

Ingress replication disabling

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BGP route filtering

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EVPN Route Type 4 filtering

Question 9

Which command allows an operator to view the local and remote MAC addresses learned via EVPN control plane and data plane across all bridge domains on an MX Series router?

Accepted Answer

show evpn database. The 'show evpn database' command displays the EVPN routing/MAC table containing MAC addresses learned via BGP EVPN control plane and local data plane learning.

Answer

show bridge domain

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show route table inet.0

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show mpls lsp

Question 10

An engineer configures an EVPN instance with multiple bridge domains. Each bridge domain requires a unique VNI. Where are the VNI values mapped to their respective bridge domains in Junos OS?

Accepted Answer

Under routing-instances bridge-domains vni . In Junos OS, VNI values are mapped under the 'bridge-domains' hierarchy using the 'vni ' statement.

Answer

Under protocols bgp neighbor configuration

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Under interfaces loopback unit 0 vni

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Under policy-options community definition

Question 11

Which TWO of the following statements regarding EVPN Route Type 1 (Ethernet Auto-Discovery Route) are correct? (Choose two)

Accepted Answer

Type 1 routes are advertised either per-EVI or per-Ethernet Segment (ES).. Route Type 1 comes in two variants: per-EVI and per-ES. Per-EVI routes provide aliasing for load-balancing across multi-homed PEs, and per-ES routes facilitate fast convergence during node failures.

Answer

Type 1 routes are only used in single-homed network topologies.

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Type 1 routes are exclusively used for mapping IP prefixes to IP-VRFs.

Answer

Type 1 routes replace Type 3 routes for handling BUM traffic replication.

Question 12

Which TWO of the following statements accurately describe EVPN Route Type 2 (MAC/IP Advertisement Route)? (Choose two)

Accepted Answer

It can carry both a MAC address and an IP address in a single control-plane update.. Type 2 routes advertise MAC addresses and optionally host IP addresses. They play a critical role in both Layer 2 bridging and Integrated Routing and Bridging (IRB) host reachability.

Answer

It is exclusively used to elect the Designated Forwarder for multicast traffic.

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It is only generated when BUM traffic flooding occurs.

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It replaces BGP L3VPN route targets for core routing.

Question 13

When configuring EVPN multi-homing in all-active mode, which THREE key components or concepts must be properly established across the PE routers? (Choose three)

Accepted Answer

A Designated Forwarder (DF) election mechanism using Type-4 routes to determine who forwards BUM traffic.. EVPN all-active multi-homing requires a consistent Ethernet Segment Identifier (ESI) across participating PEs, an active Designated Forwarder election (governed by Type-4 routes), and split-horizon filtering to prevent traffic loops.

Answer

Enabling Spanning Tree Protocol root bridge on all leaf nodes.

Answer

Configuring OSPF as the underlay routing protocol for EVPN signaling.

Question 14

When troubleshooting EVPN control plane connectivity in Junos OS, which THREE commands provide essential diagnostic information regarding EVPN routing tables and peers? (Choose three)

Accepted Answer

show route table bgp.evpn.0. To troubleshoot EVPN control plane issues, commands like 'show route table bgp.evpn.0', 'show bgp summary', and 'show evpn database' are essential for verifying route tables, neighbor status, and MAC databases.

Answer

show mpls lsp extensive

Answer

show spanning-tree interface

Question 15

Which THREE parameters are typically included or evaluated when configuring and verifying BGP EVPN peer sessions on Junos OS devices? (Choose three)

Accepted Answer

Route targets (import and export) to control the exchange of EVPN routes between routing instances.. BGP EVPN peering requires the BGP neighbor IP/address family configuration, Route Targets for import/export control, and Route Distinguishers for uniqueness within the routing instance.

Answer

RSVP bandwidth reservation for the BGP TCP session.

Answer

Spanning tree priority configuration for the BGP peering interface.