350-501 Practice Test 2 — 10 Questions

Question 1

Which TWO statements about model-driven telemetry compared to SNMP are correct? (Choose two.)

Accepted Answer

Model-driven telemetry can stream data at sub-second intervals.. Model-driven telemetry (MDT) uses a push model where the network device streams structured data (e.g., YANG-modeled) to a collector, enabling sub-second intervals for real-time monitoring. This contrasts with SNMP's pull model, where the manager polls the device at intervals limited by CPU and network overhead, making sub-second polling impractical.

Answer

Model-driven telemetry uses UDP for transport by default.

Answer

Model-driven telemetry only sends data on change (event-driven).

Answer

Model-driven telemetry uses MIBs to define data structures.

Question 2

An SP uses model-driven telemetry to monitor queue depths on core interfaces. They observe periodic spikes in the queue depth for EF traffic, causing increased latency. Which automation technique could dynamically adjust the QoS policy to mitigate the spikes?

Accepted Answer

Use a Python script that consumes telemetry data and adjusts the EF bandwith percentage via NETCONF when queue depth exceeds a threshold.. It combines model-driven telemetry (to detect queue depth spikes in real time) with a closed-loop automation approach: a Python script consumes the telemetry data, and when the EF queue depth exceeds a threshold, it dynamically adjusts the EF bandwidth percentage via NETCONF. This directly addresses the periodic spikes by modifying the QoS policy on the fly, reducing latency without manual intervention.

Answer

Deploy NETCONF YANG modules for VRF configuration.

Answer

Configure WRED on the EF queue.

Answer

Implement streaming telemetry to collect data every 5 seconds.

Question 3

An SP is troubleshooting an MPLS L2VPN VPLS network where MAC flapping is occurring between two PEs. Which mechanism in VPLS prevents loops and ensures that a broadcast frame from one PE is not reflected back to the originating PE?

Accepted Answer

Split horizon. In a VPLS environment, split horizon is the mechanism that prevents loops by ensuring that a broadcast, multicast, or unknown unicast frame received from a pseudowire (PW) is never forwarded back to any other PW on the same PE. This rule, defined in RFC 4761 and RFC 4762, stops the originating PE from receiving its own reflected frames, thus eliminating the MAC flapping that would occur if the frame were looped through the MPLS core.

Answer

Spanning Tree Protocol (STP)

Answer

Rapid Spanning Tree Protocol (RSTP)

Answer

MAC address aging

Question 4

An SP is deploying MPLS in the core/backbone to support L3VPN services. What is the purpose of MP-BGP in an MPLS VPN architecture?

Accepted Answer

To exchange customer VPN routes and VPN labels between PE routers. MP-BGP (Multiprotocol BGP) carries VPNv4 routes between PE routers, including the VPN label, enabling customer isolation and reachability across the MPLS core.

Answer

To forward data packets across the MPLS core

Answer

To establish IGP adjacencies between PE and CE routers

Answer

To distribute MPLS labels for LSPs

Question 5

An engineer configures an SR-TE policy with a segment list containing adjacency SIDs. The required path includes a strict loose hop through a specific router. Which segment type should be used for the strict hop?

Accepted Answer

Adjacency SID for the desired link.. Adjacency SIDs force the packet to traverse a specific link. For a strict hop, the adjacency SID ensures the packet goes through that exact link. A Node SID would allow any path to the node.

Answer

Anycast SID for the group containing the router.

Answer

Binding SID (BSID) of another policy.

Answer

Node SID (Prefix SID) of the router.

Question 6

Which THREE of the following are required for successful operation of OSPFv3 in an IPv6 service provider network?

Accepted Answer

Interface activation with 'ipv6 ospf area '. OSPFv3 requires interface-level activation using the 'ipv6 ospf area ' command to enable the OSPFv3 process on a specific interface and associate it with an area. Without this, the interface will not participate in OSPFv3 neighbor discovery or routing updates, even if the process is configured globally.

Answer

OSPFv3 authentication configured

Answer

OSPFv3 LSA type 9 for link-local addresses

Question 7

Refer to the exhibit. Which statement about this BGP configuration is true?

Accepted Answer

The next-hop-self command ensures that the PE sets itself as the next-hop for routes advertised to the route reflector.. The `next-hop-self` command under the VRF address-family instructs the PE router to set its own IP address as the next-hop for routes advertised to the route reflector. This is necessary in MPLS L3VPN environments to ensure that the route reflector (and other PEs) can reach the customer prefix via the advertising PE, avoiding reachability issues when the original next-hop is not directly connected across the MPLS core.

Answer

The no synchronization command is invalid under address-family ipv4 vrf.

Answer

The send-community extended command is only needed for IPv4 unicast address family.

Answer

The redistribute ospf command will import OSPF routes into the VRF but not into BGP.

Question 8

An SP deploys EVPN to provide L2VPN services with multi-homing. The customer CE is dual-homed to two different PE routers. Which EVPN mechanism ensures that only one PE forwards traffic to the CE for a given Ethernet segment, preventing loops?

Accepted Answer

Designated Forwarder election based on ESI. Ethernet Segment Identifier (ESI) and designated forwarder (DF) election in EVPN ensure that only one PE forwards traffic to the CE for a given Ethernet segment, preventing loops.

Answer

BGP Route Reflector

Answer

MAC learning via data plane

Answer

Split horizon groups

Question 9

Which Cisco automation tool is designed for service modeling with YANG and provides lifecycle management of network services?

Accepted Answer

Cisco Network Services Orchestrator (NSO). Cisco NSO (Network Services Orchestrator) uses YANG models and NETCONF to manage service lifecycle.

Answer

Cisco APIC

Answer

Cisco Prime Infrastructure

Answer

Cisco DNA Center

Question 10

In an MPLS L3VPN network with route reflectors, what is the default behavior regarding the BGP next-hop attribute for reflected VPNv4 routes?

Accepted Answer

It leaves the next-hop unchanged from the originating PE.. In an MPLS L3VPN network with route reflectors, the default behavior for VPNv4 routes is that the route reflector does not modify the BGP next-hop attribute. This is because the next-hop should remain the address of the originating PE router to ensure proper MPLS label switching and reachability. Changing the next-hop would break the MPLS forwarding path, as the P routers rely on the IGP to reach the PE's loopback, not the route reflector's.

Answer

It sets the next-hop to 0.0.0.0.

Answer

It removes the next-hop attribute.

Answer

It sets the next-hop to the route reflector's loopback.