JNCIA-DC Juniper Associate Data Center

Which VLAN membership mode assigns a port to exactly one VLAN and removes the 802.1Q tag before forwarding frames to the end device?

• ATrunk mode
• BAccess mode
• CHybrid mode
• DTagged mode

On a QFX Series switch, which Junos configuration statement correctly defines VLAN 100 named 'servers'?

• Aset vlans servers vlan-id 100
• Bset interfaces ge-0/0/0 unit 0 family ethernet-switching vlan members 100
• Cset vlan 100 name servers
• Dset vlans 100 description servers

What is the primary purpose of a trunk port in an Ethernet switching environment?

• ATo connect a single end host to exactly one VLAN
• BTo carry tagged frames for multiple VLANs between switches or to virtualized hosts
• CTo block all VLAN traffic and act as a security boundary
• DTo aggregate multiple physical links into one logical link

Rapid Spanning Tree Protocol (RSTP) improves upon original STP primarily by doing which of the following?

• AEliminating the need for a root bridge election
• BAllowing non-root ports to reach the forwarding state faster using edge ports and rapid n…
• CDistributing traffic across all links simultaneously with no blocked ports
• DUsing VXLAN encapsulation to carry spanning tree BPDUs

Multiple Spanning Tree Protocol (MSTP) differs from RSTP by adding what capability?

• AFaster convergence using edge ports
• BMapping multiple VLANs to individual spanning tree instances to allow load balancing
• CEliminating spanning tree entirely by using VXLAN overlays
• DRunning a separate spanning tree instance per physical port

What does IEEE 802.3ad Link Aggregation (LAG) accomplish in a data center switching environment?

• AIt allows a single physical port to carry traffic for multiple VLANs simultaneously
• BIt bundles multiple physical links into one logical interface to increase bandwidth and p…
• CIt creates a virtual routing instance that spans multiple switches
• DIt encrypts inter-switch traffic using 802.1AE MACsec

What is an Integrated Routing and Bridging (IRB) interface used for on a QFX Series switch?

• ATo carry spanning tree BPDUs between switches in a loop-free topology
• BTo provide a routed Layer 3 gateway for devices in a particular VLAN
• CTo aggregate multiple physical links using LACP
• DTo extend a VXLAN VNI across multiple data center sites

In a Junos Virtual Chassis configuration on EX Series switches, what is the primary benefit?

• AMultiple physical switches appear and are managed as a single logical switch
• BEach switch in the group runs its own independent control plane and Junos instance
• CVirtual Chassis uses VXLAN tunnels to extend VLANs across geographic sites
• DVirtual Chassis replaces spanning tree by providing loop-free Layer 2 forwarding

Multi-Chassis LAG (MC-LAG) solves which specific limitation of single-chassis LAG in a data center access layer?

• ASingle-chassis LAG cannot carry tagged VLAN frames
• BSingle-chassis LAG ties the LAG to one switch, creating a single point of failure; MC-LAG…
• CSingle-chassis LAG is limited to 1 Gbps links; MC-LAG enables 100 Gbps aggregation
• DSingle-chassis LAG does not support LACP; MC-LAG introduces LACP support

What does a VXLAN Network Identifier (VNI) represent?

• AThe VLAN ID used on the underlay physical network
• BA 24-bit segment identifier that distinguishes individual VXLAN overlay networks
• CThe IP address of the VTEP responsible for encapsulating frames
• DThe BGP community value used in EVPN route advertisements

What role does a VXLAN Tunnel End Point (VTEP) play in a VXLAN overlay network?

• AIt performs spanning tree root bridge election for the VXLAN domain
• BIt encapsulates Layer 2 frames into UDP/IP packets for transport across the underlay and…
• CIt distributes MAC addresses using the Border Gateway Protocol
• DIt assigns VNIs to VLANs using DHCP-like negotiation

In a VXLAN overlay, which statement best describes the relationship between the overlay and the underlay?

• AThe overlay carries control-plane routing between spine and leaf switches
• BThe overlay carries tenant Layer 2 traffic encapsulated over the underlay IP routed netwo…
• CThe underlay runs VXLAN tunnels and the overlay runs OSPF or eBGP
• DThe overlay and underlay share the same VLAN namespace and routing table

How does EVPN (Ethernet VPN) improve upon flood-and-learn MAC address discovery in a VXLAN fabric?

• AEVPN eliminates the need for VTEPs by using Multiprotocol Label Switching
• BEVPN uses BGP to distribute MAC and IP reachability information, reducing BUM (Broadcast,…
• CEVPN replaces the IP underlay with a Layer 2-only fabric between spines and leaves
• DEVPN requires all VTEPs to be co-located in the same physical rack

In a BGP EVPN control plane, which route type is used to advertise MAC address and IP address binding information?

• ARoute Type 1 (Ethernet Auto-Discovery)
• BRoute Type 2 (MAC/IP Advertisement)
• CRoute Type 3 (Inclusive Multicast Ethernet Tag)
• DRoute Type 5 (IP Prefix Route)

In a spine-leaf (Clos) IP fabric architecture, which statement is most accurate?

• AEvery leaf switch connects directly to every other leaf switch for east-west traffic
• BEvery leaf switch connects to every spine switch, and spines do not connect to each other
• CSpine switches connect to exactly two leaf switches each to create a ring topology
• DLeaf switches peer with each other using iBGP to exchange routing information

Why is eBGP (External BGP) preferred over iBGP for the underlay routing protocol in a Juniper IP fabric?

• AeBGP does not require a route reflector, and assigning a unique AS per device simplifies…
• BeBGP provides faster convergence than iBGP because it uses hello intervals instead of hol…
• CeBGP is mandatory for VXLAN encapsulation, whereas iBGP cannot encapsulate traffic
• DiBGP requires all spines and leaves to share the same VLAN, which is impractical in a rou…

Which Juniper hardware series is purpose-built for data center leaf and spine switching with high-density 10/25/100/400GbE ports?

• AMX Series
• BSRX Series
• CQFX Series
• DPTX Series

What is the positioning of the QFX5100 in Juniper's data center portfolio?

• AA spine-only switch with 400GbE ports designed for hyperscale core deployments
• BA 1/10GbE top-of-rack leaf switch commonly used for server connectivity and access-layer…
• CA modular chassis designed exclusively for service provider WAN aggregation
• DA firewall appliance with integrated switching for micro-segmentation

What is Juniper Apstra and what problem does it solve in data center operations?

• AA next-generation firewall that inspects VXLAN-encapsulated tenant traffic for threats
• BAn intent-based networking platform that automates data center fabric design, deployment,…
• CA BGP route reflector appliance that centralizes EVPN MAC/IP advertisement
• DA hardware load balancer that distributes traffic across spine switches using ECMP

Which Junos CLI command would you use to view the current active configuration on a QFX data center switch?

• Ashow interfaces
• Bshow configuration
• Crequest system configuration
• Ddisplay running-config

On a QFX switch, how do you commit a configuration change in Junos?

• AType 'save' from configuration mode
• BType 'commit' from configuration mode to make candidate configuration active
• CType 'write memory' from configuration mode
• DChanges in Junos are auto-committed 30 seconds after entry with no explicit command needed

What is the Junos command to create a VLAN named 'storage' with VLAN ID 200 on a QFX switch?

• Aset vlans storage vlan-id 200
• Bvlan 200 name storage
• Cset interfaces vlan unit 200 family inet
• Dadd vlan id 200 name storage

When configuring an interface as an access port for VLAN 100 on a QFX switch using Junos ELS, which configuration stanza is correct?

• Aset interfaces ge-0/0/1 unit 0 family ethernet-switching interface-mode access vlan membe…
• Bset interfaces ge-0/0/1 access vlan 100
• Cset interfaces ge-0/0/1 switchport access vlan 100
• Dset interfaces ge-0/0/1 unit 0 vlan-id 100

In a VXLAN configuration on a QFX switch, what does mapping a VNI to a VLAN accomplish?

• AIt routes traffic between the VLAN and the external internet using NAT
• BIt associates local VLAN 802.1Q traffic with a specific VXLAN segment so it can be tunnel…
• CIt enables spanning tree between the VLAN and the VXLAN domain
• DIt assigns a BGP community value to all traffic leaving that VLAN

Which Junos command would you use to verify that a VXLAN VNI has been configured and is operational on a QFX switch?

• Ashow vxlan tunnel
• Bshow vxlan vni all
• Cshow interfaces vxlan
• Dshow route vxlan

Which command verifies MAC address table entries on a Junos QFX switch to confirm that a host has been learned on a specific VLAN?

• Ashow arp
• Bshow ethernet-switching table
• Cshow route inet.0
• Dshow spanning-tree bridge

In a Junos EVPN-VXLAN deployment, what is the role of a BGP route reflector?

• AIt performs VXLAN encapsulation and decapsulation for all tenant traffic
• BIt eliminates the need for full-mesh iBGP sessions by reflecting EVPN routes between VTEP…
• CIt assigns VNI numbers to VLANs dynamically using DHCP
• DIt acts as the VTEP for leaf switches that do not support hardware VXLAN

In a spine-leaf fabric, what is the purpose of an anycast gateway IRB?

• ATo run a single IP gateway address on all leaf switches simultaneously so VMs can migrate…
• BTo load-balance BGP updates across multiple spine switches
• CTo provide a secondary IP address for out-of-band management access
• DTo bind a VNI to a specific MAC address for EVPN type-2 routes

Which OSPF area type would be most appropriate for underlay routing on a small spine-leaf fabric where all links are between leaf and spine?

• AOSPF Area 0 (backbone area) connecting all devices with no stub or NSSA areas
• BOSPF totally stubby area (no-summary) to reduce LSA flooding to leaf switches
• COSPF NSSA area to allow leaf switches to redistribute external routes
• DOSPF virtual links because spines and leaves cannot be directly connected

What is the minimum configuration required on a QFX leaf switch to enable VXLAN encapsulation for a specific VLAN?

• ADefine the VLAN, assign it a VNI, and configure a local VTEP source address (loopback)
• BEnable OSPF on all interfaces and define a BGP neighbor for each remote VTEP
• CConfigure an IRB interface for the VLAN and assign a static MAC address
• DCreate a routing-instance of type virtual-router and attach the VLAN

What is the purpose of an ICL (Inter-Chassis Link) in an MC-LAG deployment?

• ATo carry encapsulated VXLAN traffic between the two MC-LAG peers
• BTo synchronize control-plane state (MAC tables, LACP PDUs, ARP/ND) between the two MC-LAG…
• CTo provide an out-of-band management channel between the two MC-LAG peers
• DTo run spanning tree between the two MC-LAG peers as a loop-prevention mechanism

In a Junos data center deployment, what does the 'show lacp interfaces' command verify?

• AThat spanning tree has elected the correct root bridge for all VLANs
• BThat LACP PDU negotiation is active and the expected member links are bundled in the ae i…
• CThat VXLAN VNIs are mapped to the correct VLANs
• DThat BGP sessions are established with all EVPN peers

What QFX5200 feature differentiates it from the QFX5100 in terms of forwarding capacity and port density?

• AThe QFX5200 adds hardware VXLAN termination and supports higher density 25/100GbE ports c…
• BThe QFX5200 is a modular chassis with replaceable linecards, while the QFX5100 is a fixed…
• CThe QFX5200 runs a different operating system (Junos Evo) exclusively, while the QFX5100…
• DThe QFX5200 supports only spine roles, while the QFX5100 supports only leaf roles

In Junos, which routing instance type is used to create separate VRFs for tenant isolation in an EVPN-VXLAN data center?

• Ainstance-type forwarding
• Binstance-type virtual-router or evpn
• Cinstance-type layer2-control
• Dinstance-type no-forwarding

What is the function of the ICCP (Inter-Chassis Control Protocol) in an MC-LAG deployment?

• AIt provides VXLAN tunnel negotiation between the two MC-LAG peers
• BIt synchronizes operational state such as MAC tables, LACP information, and link status b…
• CIt runs as a BGP extension to exchange EVPN routes across the ICL
• DIt assigns unique LACP system IDs to each peer to avoid LACP conflicts

Which spanning tree port role is assigned to the port through which a non-root bridge receives the best path to the root bridge?

• ADesignated port
• BRoot port
• CAlternate port
• DBackup port

In the context of Juniper Apstra's intent-based networking model, what does 'intent' refer to?

• AA BGP community string that signals traffic engineering preferences
• BThe desired high-level state of the network described by the operator, which Apstra trans…
• CA Junos commit script that validates configuration before applying
• DThe OSPF area type assigned to each link in the fabric underlay

What is the significance of a loopback interface (lo0) in a data center spine-leaf fabric?

• AIt provides the source IP address for VTEP encapsulation and is advertised via the underl…
• BIt serves as the management interface for Junos Zero Touch Provisioning (ZTP)
• CIt carries all BUM (Broadcast, Unknown, Multicast) traffic between leaf switches
• DIt holds the VXLAN VNI definitions for the local fabric segment

In Junos, what does the 'show bgp summary' command display in the context of an EVPN fabric?

• AThe MAC address table learned via BGP EVPN type-2 routes
• BThe status of all configured BGP neighbor sessions including their state, number of prefi…
• CThe spanning tree root bridge and port states for each VLAN
• DThe VNI-to-VLAN mapping table managed by the EVPN control plane

What distinguishes the QFX10000 Series from the QFX5000 Series in a data center fabric context?

• AQFX10000 is a modular chassis-based platform designed for high-capacity spine roles, whil…
• BQFX10000 runs a proprietary non-Junos OS, while QFX5000 runs standard Junos
• CQFX10000 supports only Layer 3 routing and cannot perform any Layer 2 switching
• DQFX10000 is limited to 10GbE ports and cannot support 100GbE or higher speeds

A QFX leaf switch is connected to a server via an access port. When the server sends an untagged Ethernet frame, what does the switch do with it?

• ADrops the frame because untagged frames are not permitted on QFX switches
• BForwards the frame on the native VLAN and tags it internally with the access port's VLAN…
• CSends the frame to the route engine for Layer 3 processing
• DFloods the frame out of all trunk ports regardless of the configured VLAN

What does 'BUM traffic' stand for in a VXLAN overlay, and how does ingress replication handle it?

• ABorder Underlay Multicast; handled by OSPF multicast groups in the underlay
• BBroadcast, Unknown unicast, and Multicast; the ingress VTEP copies the frame and sends a…
• CBroadcast, Unicast, Multicast; handled by EVPN type-3 routes as multicast group assignmen…
• DBlocked Unknown Multicast; dropped by default unless IGMP snooping is enabled

In a Junos data center switch configuration, what is the role of the 'family ethernet-switching' statement under an interface unit?

• AIt enables Layer 3 IP routing on the interface
• BIt activates Layer 2 switching mode on the interface, allowing VLAN membership and MAC le…
• CIt enables VXLAN encapsulation on the interface
• DIt assigns an IPv6 address to the interface for management access

What is the primary advantage of using eBGP with unique AS numbers per device versus a single AS for the entire fabric?

• AUnique AS numbers per device cause BGP to automatically detect and drop duplicate route a…
• BA single fabric-wide AS would require iBGP full-mesh or route reflectors; unique per-devi…
• CUnique AS numbers enable VXLAN encapsulation, which is not possible with a single AS numb…
• DA single fabric-wide AS limits the number of BGP neighbors to 255; unique ASNs remove thi…

What is the QFX5700's primary use case in a Juniper data center fabric?

• AEntry-level top-of-rack leaf switch for 1GbE server connectivity
• BHigh-density 400GbE spine or high-capacity leaf switch for hyperscale and large enterpris…
• CDedicated firewall and intrusion prevention for north-south traffic
• DWAN edge router for connecting the data center to internet upstreams

In a Junos EVPN-VXLAN configuration, what is the purpose of the 'route-distinguisher' (RD) configured in the routing-instance?

• ATo uniquely identify VNI segments so the VTEP can distinguish overlay networks from each…
• BTo make EVPN routes unique in the BGP table when the same IP prefix or MAC exists in mult…
• CTo set the BGP local preference for all EVPN routes received from remote VTEPs
• DTo define the OSPF area number for the routing instance's underlay links

In Junos, which command enters configuration mode so you can make changes to the candidate configuration?

• Aconfigure
• Bedit
• Cenable
• Dconf t