Juniper JN0-481 Dumps Questions Answers

Referring to the exhibit, the image shows a simplified diagram of an IP fabric network connecting two servers, labeled as Server A and Server B. The IP fabric is a network architecture that uses a Clos topology to provide high bandwidth, low latency, and scalability for data center networks. The IP fabric consists of spine and leaf devices that use BGP as the routing protocol and VXLAN as the overlay technology1.

A broadcast domain is a logical portion of a network where any device can directly transmit broadcast frames to other devices at the data link layer (OSI Layer 2). A broadcast frame is a frame that has a destination MAC address of all ones (FF:FF:FF:FF:FF:FF), which means that it is intended for all devices in the same broadcast domain. A broadcast domain is usually bounded by a router, which does not forward broadcast frames to other networks2.

In the exhibit, there are two broadcast domains that an Ethernet frame will pass through when traversing the IP fabric from Server A to Server B. The first broadcast domain is the one that contains Server A and the leaf device that it is connected to. The second broadcast domain is the one that contains Server B and the leaf device that it is connected to. The IP fabric itself is not a broadcast domain, because it uses IP routing and VXLAN encapsulation to transport the Ethernet frames over the Layer 3 network. Therefore, the statement C is correct in this scenario.

The following three statements are incorrect in this scenario:

A. 1. This is not true, because there are not one, but two broadcast domains that an Ethernet frame will pass through when traversing the IP fabric from Server A to Server B. The IP fabric itself is not a broadcast domain, because it uses IP routing and VXLAN encapsulation to transport the Ethernet frames over the Layer 3 network.

B. 4. This is not true, because there are not four, but two broadcast domains that an Ethernet frame will pass through when traversing the IP fabric from Server A to Server B. The spine devices and the leaf devices that are not connected to the servers are not part of the broadcast domains, because they use IP routing and VXLAN encapsulation to transport the Ethernet frames over the Layer 3 network.

D. 3. This is not true, because there are not three, but two broadcast domains that an Ethernet frame will pass through when traversing the IP fabric from Server A to Server B. The IP fabric itself is not a broadcast domain, because it uses IP routing and VXLAN encapsulation to transport the Ethernet frames over the Layer 3 network.

A three-stage Clos (leaf–spine) data center fabric separates roles to keep forwarding predictable and scalable. The leaf layer is the attachment point for endpoints, so servers connect to leaf devices. This is where the fabric accepts workload traffic, applies edge policies, and provides tenant/service constructs (for EVPN-VXLAN fabrics, the leafs typically act as VTEPs and host IRB gateways as required). The spine layer provides the non-blocking transit core between leafs using L3 underlay routing and ECMP, but it is not the place where servers attach directly.

For north-south connectivity, a typical three-stage Apstra data center architecture includes border leaf switches. These border devices provide the controlled connection point between the fabric and external networks (Internet/WAN/DCI or upstream services). As a result, fabric traffic enters and exits the border devices, not the spines. This design keeps the spines dedicated to high-speed east-west transit and simplifies operations: external routing policies, security controls, and inter-domain handoffs are concentrated at the border, while the spines remain a uniform L3 transit tier. In Junos v24.4 EVPN-VXLAN deployments, this separation also helps maintain clean overlay boundaries and consistent underlay behavior across the fabric.

Verified Juniper sources (URLs):

https://www.juniper.net/documentation/us/en/software/juniper-data-center-assurance/user-guide/topics/concept/dc-network-topology-on-dc-assurance.html

https://www.juniper.net/documentation/us/en/software/jvd/jvd-3-stage-datacenterdesign-with-juniper-apstra/solution_architecture.html

https://www.juniper.net/content/dam/www/assets/white-papers/us/en/design-considerations-for-spine-and-leaf-ip-fabrics.pdf

In Junos EVPN, the service type determines how VLANs (broadcast domains) are mapped into EVPN constructs. With VLAN-based service, the mapping is one-to-one: a single VLAN (single broadcast domain) maps to a single EVPN instance (EVI), resulting in a separate bridge table per VLAN. When you implement EVPN-VXLAN in a bridged overlay (L2 extension over an L3 underlay), leaf devices act as VTEPs and encapsulate VLAN traffic into VXLAN using the associated VNI, but the service-type mapping rule still applies.

At the MAC-VRF hierarchy, you configure the EVPN-VXLAN parameters and choose the service type for that EVPN instance. If the service type selected is VLAN-based, then the EVI represents exactly one VLAN at that EVPN instance level. If you need multiple VLANs under the same MAC-VRF/EVI construct, Junos provides alternative service types (for example, VLAN-aware or VLAN-bundle) specifically intended to associate multiple VLANs with a single EVPN instance; that is not what VLAN-based service does.

Therefore, in a bridged overlay EVPN-VXLAN design using VLAN-based service at the MAC-VRF EVPN instance level, the correct answer is one VLAN. This remains true regardless of how many total VLANs exist across the fabric; each VLAN-based EVI handles a single VLAN.

Verified Juniper sources (URLs):

https://www.juniper.net/documentation/us/en/software/junos/evpn/topics/concept/evpn-based-services.html

https://www.juniper.net/documentation/us/en/software/junos/evpn/topics/concept/mac-vrf-routing-instance-overview.html