Free JNCIP-DC Practice Questions

Question 1

A QFX leaf delivers same-subnet unicast to a remote host when the local test host has a static ARP entry. After that test entry is removed, the initial ARP request is flooded despite ARP suppression being enabled. The remote Type 2 route reports MAC length 48 and IP-address length 0; the leaf's EVPN ARP table has no entry for the target IP. These observations indicate that:

Accepted Answer

Bridging works, but ARP suppression lacks the required IP-to-MAC binding.

Answer

MAC-only Type 2 routes cannot forward remote unicast.

Answer

ARP suppression requires a Type 5 route for the subnet.

Answer

Only locally received ARP traffic can populate the EVPN suppression table.

Question 2

A packet capture shows a congested fabric switch changing a RoCEv2 packet's ECN field to 11. The packet then reaches the destination NIC without being dropped. RoCEv2 congestion control is enabled at both endpoints. Which event completes the expected congestion-feedback path?

Accepted Answer

The receiver sends a congestion notification packet to the original sender.

Answer

The switch sends a congestion notification packet to the original sender.

Answer

The sender requests a congestion notification from the receiver.

Answer

The receiver sends a PFC pause frame toward the source across the routed fabric.

Question 3

The ZTP file service has moved from 192.0.2.20 to 192.0.2.30; the DHCP service has not moved. A newly connected QFX switch obtains an IPv4 lease but requests leaf17.conf from the old file server, which returns HTTP 404. Its DHCP ACK contains option 150 = 192.0.2.20, option 66 = 192.0.2.30, and option 43 suboption 01 = leaf17.conf. HTTP is supported, and the file is available at the new server. Which DHCP change directs the next provisioning attempt to the intended file server?

Accepted Answer

Set option 150 to 192.0.2.30 while retaining the configuration filename.

Answer

Remove option 66 and retain option 150.

Answer

Set option 54 to 192.0.2.30, leaving the other options unchanged.

Answer

Move leaf17.conf from suboption 01 to suboption 00 of option 43.

Question 4

Two hosts in the same subnet exchange traffic through an IPv4 VXLAN tunnel. A routed spine between their VTEPs performs no VXLAN termination or tenant routing. Captures on the ingress and egress sides of that spine are compared for the same packet. How should the two IPv4 TTL fields change?

Accepted Answer

Only the outer IP TTL decreases.

Answer

Only the inner IP TTL decreases.

Answer

Neither IP TTL changes before tunnel termination.

Answer

Both the inner and outer IP TTLs decrease.

Question 5

During an isolation incident, tenant A begins reaching tenant B's 10.44.0.0/24 through a newly imported EVPN Type 5 route carrying target:65000:200. That is A's only route to the subnet, while B's other sites depend on the same exported route. A's own routes use target:65000:100, and required shared services use target:65000:900; its import policy now accepts all three. The tenants have distinct route distinguishers. Which immediate change removes the unauthorized reachability while preserving both tenants' legitimate traffic?

Accepted Answer

Remove A's import of target:65000:200 and withdraw the imported route from A.

Answer

Disable tenant A's border uplinks until the policy audit finishes.

Answer

Re-advertise tenant B's prefix with a new route distinguisher and the same route target.

Answer

Remove target:65000:200 from tenant B's route-export policy on every leaf.

Question 6

A server uses one LACP bundle across two EVPN leaves in all-active mode. Both leaves advertise the same Ethernet segment identifier. Leaf-A is the designated forwarder; Leaf-B is non-DF. Captures show different known-unicast flows reaching the server through both leaves, while network-originated broadcasts reach it only through Leaf-A. An operator proposes disabling Leaf-B's server-facing link to prevent a loop. How should this proposal be assessed?

Accepted Answer

Keep both links active; the observed forwarding is consistent with all-active operation.

Answer

Disable Leaf-B's link because a non-DF must remain a standby for all traffic.

Answer

Move the segment to single-active because all-active permits duplicate broadcast delivery.

Answer

Increase Leaf-B's DF preference because receiving unicast requires it to become DF.

Question 7

After a RoCEv2 rack is moved onto untagged routed fabric links, its packets appear in the best-effort queue during congestion. The hosts still mark them DSCP 26. The switch supports DSCP-based PFC; its attached PFC profiles, DSCP 26 to PFC priority 3 mapping, RDMA no-loss queue, and peer settings are correct. The new ingress ports, however, apply only an IEEE 802.1p classifier. Which change restores the intended RDMA treatment while keeping ordinary traffic in its own class?

Accepted Answer

Classify ingress DSCP 26 into the RDMA forwarding class.

Answer

Rewrite egress DSCP 26 to DSCP 3.

Answer

Enable PFC for priority 0 in addition to priority 3.

Answer

Increase the scheduler weight assigned to the RDMA queue.

Question 8

Review this selective DCI configuration: DC-A must retain local VNI 50120, DC-B must retain local VNI 60120, and only the ANALYTICS service may span the WAN. Both gateways set translation-vni 90120, but each interconnected-vni-list contains only its local VNI. Other services already have translation mappings but must remain local. The underlay, EVPN sessions, and route-target policies are correct. What should appear in each gateway's interconnected-vni-list?

Accepted Answer

Only the common WAN VNI, 90120.

Answer

Only the peer site's local VNI.

Answer

All VNIs with a configured translation mapping.

Answer

Both local VNIs, 50120 and 60120.

Question 9

In a symmetric-IRB tenant, a host on Leaf-A in L2 VNI 5010 sends to another subnet on Leaf-B in L2 VNI 5020. Both leaves use tenant L3 VNI 50000; the required routes and neighbor entries are installed. Predict the VNI carried across the fabric and the operation performed when Leaf-B receives the packet.

Accepted Answer

VNI 50000; perform a tenant IP lookup, then bridge toward the host.

Answer

VNI 5020; bridge directly into the destination subnet without a tenant IP lookup.

Answer

VNI 5010; route from the source bridge domain into the destination subnet.

Answer

VNI 50000; bridge to the host without routing.

Question 10

A 10-Gb/s egress interface reports 8,500,000,000 transmitted octets at 10:00:00 and 12,250,000,000 at 10:00:30. The counter neither resets nor wraps. During those same 30 seconds, queue telemetry records repeated near-full occupancy peaks and 1,900 additional tail-dropped packets; physical error and carrier-transition counters remain unchanged. Which interpretation accounts for both the traffic rate and the loss?

Accepted Answer

10% average utilization; short congestion bursts can still exhaust the available egress queue space.

Answer

1.25% average utilization; the drops point to physical faults rather than egress queue pressure.

Answer

32.7% average utilization; the increasing octet total shows that traffic remained steadily above queue capacity.

Answer

100% average utilization; sustained line-rate saturation accounts for the queue peaks and packet drops.

Free JNCIP-DC Practice Questions

Domain 1: Data Center Deployment and Management

Question 1

Question 2

Domain 2: Layer 3 Fabrics

Question 3

Question 4

Domain 3: VXLAN

Question 5

Domain 4: EVPN-VXLAN Signaling

Question 6

Question 7

Question 8

Domain 5: Data Center Interconnect

Question 9

Domain 6: Data Center Multitenancy and Security

Question 10

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