Juniper JN0-683 Exam Actual Questions

Scenario Overview:

In the exhibit, Host A is trying to resolve Host B's IP address (10.10.1.2) through ARP (Address Resolution Protocol). Normally, an ARP request would be broadcasted over the network, and the host owning the IP address (Host B) would respond.

Role of Proxy ARP:

Option A: Proxy ARP allows a router or switch (in this case, leaf1) to respond to ARP requests on behalf of another host. Leaf1, knowing the MAC address of Host B through the EVPN MAC advertisement, can reply to Host A's ARP request directly without broadcasting the request across the entire network fabric. This feature reduces unnecessary traffic and increases network efficiency.

Conclusion:

Option A: Correct---Proxy ARP enables leaf1 to respond to Host A's ARP request for Host B's IP without broadcasting over the IP fabric, thus providing the ARP response locally.

Understanding Oversubscription in a Clos Fabric:

The oversubscription ratio in a Clos IP fabric measures the ratio of the amount of edge (leaf) bandwidth to the core (spine) bandwidth. An oversubscription ratio of 3:1 means that there is three times more edge bandwidth compared to core bandwidth.

Impact of Adding/Removing Spine Devices:

Option C: If you remove spine devices, the total available core bandwidth decreases, while the edge bandwidth remains the same. This results in an increase in the oversubscription ratio because there is now less core bandwidth to handle the same amount of edge traffic.

Option B: Conversely, if you add spine devices, the total core bandwidth increases. This decreases the oversubscription ratio because more core bandwidth is available to handle the edge traffic.

Conclusion:

Option C: Correct---Removing spine devices increases the oversubscription ratio.

Option B: Correct---Adding spine devices decreases the oversubscription ratio.

Analyzing the Exhibit Output:

The command ping overlay tunnel-type vxlan is used to test the VXLAN tunnel between two VTEPs (VXLAN Tunnel Endpoints). The output shows a warning about missing hash parameters, but more importantly, it displays the result: End-System Not Present.

Understanding the Response:

The message End-System Not Present indicates that the remote VTEP (192.168.2.20) did not find the MAC address 00:00:5E:00:53:CC in its forwarding table. This typically means that the MAC address is unknown to the remote VTEP, and as a result, it could not forward the packet to the intended destination.

Conclusion:

Option B: Correct---The MAC address is unknown and is not in the forwarding table of the remote VTEP, which is why the system reports that the 'End-System' is not present.

Requirement Analysis:

The scenario requires a solution to interconnect two data centers that supports EVPN Type 2 connectivity. The solution must be highly scalable and must minimize the number of VXLAN tunnels between border leaf devices.

Understanding Type 2 Seamless Stitching:

Option D: Type 2 seamless stitching is a method used in EVPN to provide Layer 2 connectivity (such as MAC address mobility) across different VXLAN segments. It is scalable because it allows only necessary tunnels to be established between border leaf devices, reducing the overhead of maintaining a full mesh of VXLAN tunnels.

Conclusion:

Option D: Correct---Type 2 seamless stitching satisfies the requirement by enabling scalable, efficient interconnection of two data centers with minimal VXLAN tunnels.

EVPN-VXLAN Configuration:

The configuration provided in the exhibit shows an EVPN-VXLAN setup where IP prefix routes are exchanged between two sites. The advertise direct-nexthop option and the VNI (Virtual Network Identifier) settings are crucial in this context.

Advertise Direct-Nexthop:

Option A: The advertise direct-nexthop option ensures that the next-hop route is resolved using only the information carried in the EVPN Type 5 route. Type 5 routes are used for IP prefix advertisement in EVPN, which is key to enabling Layer 3 interconnectivity between different VXLAN segments.

VNI Consistency:

Option C: For the same customer across different devices, the VNI must be consistent. This consistency ensures that all devices can correctly map traffic to the appropriate VXLAN segment, maintaining seamless Layer 2 and Layer 3 connectivity.