Juniper JN0-480 Data Center, Specialist Exam Practice Test

Answer : A, D

Probes are the basic unit of abstraction in Intent-Based Analytics (IBA). They are used to collect, process, and analyze data from the network and raise anomalies based on specified conditions. Probes are composed of processors and stages that form a directed acyclic graph (DAG) of data flow. The following statements are correct about probes:

A) Default probes can be cloned, modified, and saved. This is true because Apstra provides a set of default probes that cover common use cases and scenarios. These probes can be cloned and modified to suit the specific needs of the user. The modified probes can be saved as new probes with different names and descriptions. This allows the user to customize and extend the functionality of the default probes.

D) Default probes are enabled, based on the intent for a blueprint. This is true because Apstra enables or disables the default probes automatically based on the intent of the blueprint. The intent of the blueprint is the high-level description of the desired state and behavior of the network. Apstra uses the intent to determine which default probes are relevant and applicable for the blueprint and enables them accordingly. For example, if the intent of the blueprint is to deploy an EVPN-VXLAN fabric, Apstra will enable the default probes related to EVPN-VXLAN, such as EVPN-VXLAN Anomaly Detection, EVPN-VXLAN Fabric Health, and EVPN-VXLAN Fabric Validation. The following statements are incorrect about probes:

B) Only the variable parameters for default probes can be edited and saved. This is false because the user can edit and save any parameters for the default probes, not just the variable ones. The variable parameters are the ones that depend on the network topology, devices, or configuration, such as device names, interface names, IP addresses, VLAN IDs, etc. The user can also edit and save the fixed parameters, such as the duration, threshold, condition, etc. However, the user cannot edit and save the default probes directly. The user must clone the default probes first and then edit and save the cloned probes as new probes.

C) All default probes are enabled for all blueprints. This is false because Apstra does not enable all default probes for all blueprints. Apstra enables the default probes based on the intent of the blueprint, as explained above. This means that only the default probes that are relevant and applicable for the blueprint are enabled. For example, if the intent of the blueprint is to deploy a BGP IP fabric, Apstra will not enable the default probes related to EVPN-VXLAN, since they are not relevant for the blueprint. The user can also manually enable or disable the default probes as needed.Reference:

Probes

Create Probe

Intent-Based Analytics Overview

Answer : B

VMware anomaly detection is a feature of Apstra that provides visibility and validation of the virtual network settings and the physical network settings in a VMware vSphere environment. To enable this feature, Apstra requires a connection to a vCenter server that manages the ESX/ESXi hosts and the VMs connected to the Apstra-managed leaf switches. The vCenter server must be configured under External Systems in the Apstra web interface, and the vCenter integration must be staged and committed in the blueprint. This allows Apstra to collect information about VMs, ESX/ESXi hosts, port groups, and VDS, and to flag any inconsistencies or mismatches that might affect VM connectivity. The other options are incorrect because:

VMware anomaly detection is not on by default. It must be enabled by configuring a vCenter server under External Systems and adding a virtual infra to the blueprint.

VMware anomaly detection does not require a VMware hypervisor with exports enabled. It only requires LLDP transmit to be enabled on the VMware distributed virtual switch to associate host interfaces with leaf interfaces.

VMware anomaly detection does not require an Apstra server running on VMware. It can run on any supported platform, such as Linux, Windows, or Docker.Reference:

VMware vCenter/vSphere Virtual Infra

Anomalies (Service)

A Better Experience: VMware + Juniper Apstra

Answer : D

The Links table in the Staged tab shows the physical connections between the devices in the fabric. It provides information such as the source and destination device names, hostnames, serial numbers, roles, interfaces, and link status. The Links table can be used to assist the team that is installing and cabling the devices by verifying that the devices are connected correctly and that the links are operational. The Links table can also be used to troubleshoot any connectivity issues that may arise during the installation process. For more information, seeLinks (Staged).Reference:

Links (Staged)

Topology (Staged)

Staged

Answer : A

The leaf device in AS 65000 will receive three routes for the 10.100.0.0/16 prefix, one from each spine device in AS 65001, AS 65002, and AS 65003. Since ECMP load balancing is enabled, the leaf device will install all three routes in its routing table and distribute the traffic among them. The other options are incorrect because:

B) 1 is wrong because the leaf device will not receive only one route for the prefix. It will receive multiple routes from different spine devices and use ECMP to load balance among them.

C) 2 is wrong because the leaf device will not receive only two routes for the prefix. It will receive three routes from three spine devices, as explained above.

D) 4 is wrong because the leaf device will not receive four routes for the prefix. It will receive three routes from three spine devices, as explained above. The fourth spine device in AS 65004 is not directly connected to the leaf device and will not advertise the prefix to it.Reference:

IP Fabric Underlay Network Design and Implementation

BGP Multipath load sharing iBGP and eBGP

ECMP Load Balancing

Answer : C, D

In the EVPN-VXLAN data center fabric bridged overlay architecture shown in the exhibit, the servers are connected to Leaf1 and Leaf6 using the same virtual network identifier (VNI). This means that the servers belong to the same Layer 2 domain and can communicate with each other using VXLAN tunnels across the fabric. The underlay network provides the IP connectivity between the leaf and spine devices, and it uses EBGP as the routing protocol. Therefore, the following two statements are correct in this scenario:

Loopback IPv4 addresses must be advertised into the EBGP underlay from leaf and spine devices. This is because the loopback addresses are used as the source and destination IP addresses for the VXLAN tunnels, and they must be reachable by all the devices in the fabric. The loopback addresses are also used as the router IDs and the BGP peer addresses for the EBGP sessions.

The underlay EBGP peering's must be established between leaf and spine devices. This is because the EBGP sessions are used to exchange the underlay routing information and the EVPN routes for the overlay network. The EBGP sessions are established using the loopback addresses of the devices, and they follow a spine-and-leaf topology, where each leaf device peers with all the spine devices, and each spine device peers with all the leaf devices.

The following two statements are incorrect in this scenario:

The underlay must use IRB interfaces. This is not true, because the underlay network does not provide any Layer 3 gateway functionality for the overlay network. The IRB interfaces are used to provide inter-VXLAN routing within the fabric, which is not the case in the bridged overlay architecture. The IRB interfaces are used in the edge-routed bridging (ERB) or the centrally-routed bridging (CRB) architectures, which are different from the bridged overlay architecture.

The underlay must be provisioned with PIMv2. This is not true, because the underlay network does not use multicast for the VXLAN tunnels. The VXLAN tunnels are established using EVPN, which uses BGP to distribute the MAC and IP addresses of the end hosts and the VTEP information of the devices. EVPN eliminates the need for multicast in the underlay network, and it provides optimal forwarding and fast convergence for the overlay network.

Exploring EVPN-VXLAN Overlay Architectures -- Bridged Overlay

EVPN LAGs in EVPN-VXLAN Reference Architectures

EVPN-VXLAN Configuration Guide

Answer : D

According to the Juniper documentation1, a routing zone is an L3 domain, the unit of tenancy in multi-tenant networks. You create routing zones for tenants to isolate their IP traffic from one another, thus enabling tenants to re-use IP subnets. In addition to being in its own VRF, each routing zone can be assigned its own DHCP relay server and external system connections. You can create one or more virtual networks within a routing zone, which means a tenant can stretch its L2 applications across multiple racks within its routing zone. For virtual networks with Layer 3 SVI, the SVI is associated with a Virtual Routing and Forwarding (VRF) instance for each routing zone isolating the virtual network SVI from other virtual network SVIs in other routing zones. If you're using multiple routing zones, external system connections must be from leaf switches in the fabric. Routing between routing zones must be accomplished with external systems. Therefore, the correct answer is D. Use interconnection through an external gateway.Reference:Routing Zones

Answer : D

A graph query is a component that identifies devices that supply data for a specific probe. A graph query is an expression that matches nodes in the Apstra graph database based on their attributes, such as device name, role, type, or tag.A graph query can be used to select the source devices for the input processors of a probe, as well as to filter the data by device attributes in the subsequent processors of a probe12.Reference:

Probes

Apstra IBA Getting Started Tutorial