350-501 Architecture Practice Test 13 — 15 Questions

Question 1

In IOS XR, which process is responsible for managing the configuration database and commit operations?

Accepted Answer

confd. In IOS XR, the confd process is responsible for managing the configuration database and commit operations. It handles configuration changes, validation, and commits, ensuring that the system configuration is consistent and applied atomically.

Answer

fman

Answer

sysmgr

Answer

rib

Question 2

A service provider is using NSO for service orchestration. Which protocol does NSO use to communicate with network devices for configuration?

Accepted Answer

NETCONF. Cisco NSO (Network Services Orchestrator) is built around NETCONF/YANG as its primary southbound interface for communicating with network devices. NETCONF provides a standardized, transactional, candidate-config-based mechanism to push configuration and retrieve state, which NSO uses to render and deploy services across multivendor devices. This makes NETCONF the native protocol NSO relies on for configuration management.

Answer

SNMP

Answer

RESTCONF

Answer

CLI scripting

Question 3

Which TWO are characteristics of the access layer in a service provider network? (Choose two.)

Accepted Answer

Provides connectivity to end customers. Option A is correct because the access layer in a service provider network is the portion that directly connects subscribers and end customers to the provider's infrastructure, aggregating their traffic toward the distribution/aggregation layer. Option E is correct because the access layer is where last-mile access technologies such as DSL, cable (DOCSIS), and GPON are terminated and supported to deliver services to residential and business customers. Option B is incorrect because inter-AS MPLS is a core/edge function involving autonomous system interconnection, not a characteristic of the access layer. Option C is incorrect because MPLS label switching for core traffic occurs in the provider core, where high-speed label-switched forwarding is performed, not at the access layer. Option D is incorrect because BGP route reflection is typically implemented on core or route-reflector routers to scale iBGP within the provider backbone, not as an access-layer function.

Answer

Implements inter-AS MPLS

Answer

Uses MPLS label switching for core traffic

Answer

Performs BGP route reflection

Question 4

Which TWO are benefits of using EVPN over traditional VPLS for L2VPN services? (Choose two.)

Accepted Answer

Provides MAC address learning via control plane. EVPN offers better control plane (BGP) and supports multi-homing with all-active load balancing.

Answer

Uses LDP for label distribution

Answer

Requires full mesh of pseudowires

Answer

Simpler configuration than VPLS

Question 5

Which access technology in a service provider network uses a passive optical splitter to distribute signals to multiple customers, with typical downstream speeds up to 2.5 Gbps?

Accepted Answer

GPON. GPON is a point-to-multipoint fiber access technology using passive optical splitters, providing downstream speeds up to 2.5 Gbps and upstream up to 1.25 Gbps.

Answer

Metro Ethernet

Answer

DSL

Answer

Cable (DOCSIS)

Question 6

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) is used in MPLS L3VPNs to exchange VPN-IPv4 routes and their associated MPLS labels (VPN labels) between PE routers. It carries the route target extended communities that control import/export of routes into VRFs, enabling the PE routers to learn customer routes and the labels needed to forward traffic to the correct CE. Without MP-BGP, PEs would not have a scalable way to distribute customer routes across the provider 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 7

An SP uses Cisco ASR 9000 routers with IOS XR. Which statement correctly describes the commit/rollback configuration model in IOS XR?

Accepted Answer

Changes are staged in a candidate configuration and applied only after 'commit'; rollback to a previous commit is possible.. IOS XR uses a two-stage configuration model: changes are made in a candidate configuration and only take effect after the 'commit' command. The system maintains a rollback buffer of previous commits, allowing rollback to any of the last 10 committed configurations using 'rollback configuration' or 'load rollback changes'. This provides safe, transactional configuration changes.

Answer

Only 'commit replace' is supported; rollback requires manual re-entry.

Answer

The router automatically commits changes every 10 minutes.

Answer

Changes take effect immediately without commit; rollback is not supported.

Question 8

A service provider wants to offer a point-to-point Ethernet service between two customer sites with a defined bandwidth and performance guarantee, according to MEF standards. Which Carrier Ethernet service type is appropriate?

Accepted Answer

E-Line. MEF defines E-Line as a point-to-point Ethernet service connecting exactly two customer sites (UNIs) with a committed bandwidth and performance guarantee — matching the requirement for a dedicated point-to-point service with defined bandwidth. E-Line is the Carrier Ethernet equivalent of a leased line or EPL (Ethernet Private Line).

Answer

E-LAN

Answer

E-Access

Answer

E-Tree

Question 9

In the context of network slicing for 5G, which type of slice is optimized for massive IoT with low data rates and high connection density?

Accepted Answer

mMTC. mMTC (massive Machine Type Communication) is the 5G slice type optimized for massive IoT, characterized by low data rates, high connection density, and low power consumption. uRLLC is for ultra-reliable low-latency communications, eMBB for enhanced mobile broadband, and V2X for vehicle-to-everything communications.

Answer

uRLLC

Answer

V2X

Answer

eMBB

Question 10

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 11

Which architecture feature of IOS XR ensures that a failure in one routing protocol process does not affect other processes on the same router?

Accepted Answer

Process separation with each protocol as a separate process. IOS XR's process separation model runs each routing protocol as an independent process with its own protected memory space. If one protocol process fails (e.g., OSPF crashes), the other processes (BGP, ISIS) continue running unaffected, providing fault isolation and preventing a single protocol failure from cascading across the router.

Answer

Admin plane vs default SDR

Answer

Commit/rollback configuration model

Answer

CPU and memory allocation per card

Question 12

A service provider needs to offer L3VPN services with customer isolation. Which technology is used to maintain separate routing tables for different customers on a single PE router?

Accepted Answer

VRF. A VRF (Virtual Routing and Forwarding) instance creates a separate virtual routing table on the PE router, allowing multiple customers to share the same physical device while keeping their routing information completely isolated. Each VRF maintains its own RIB and FIB, so overlapping IP address spaces between customers do not conflict. This is the foundational mechanism for L3VPN customer isolation on a single PE.

Answer

VLAN

Answer

Route distinguisher (RD)

Answer

MPLS labels

Question 13

An SP uses Cisco NSO for automation. Which protocol does NSO typically use to push configuration changes to network devices?

Accepted Answer

NETCONF. Cisco NSO (Network Services Orchestrator) is built around YANG data models and uses NETCONF as its primary southbound protocol to push configuration changes to network devices. NETCONF provides transactional, candidate-config, and rollback capabilities that align with NSO's model-driven, intent-based automation approach.

Answer

RESTCONF

Answer

SNMP

Answer

CLI via SSH

Question 14

What is the primary function of the aggregation layer in a service provider network?

Accepted Answer

Aggregate traffic from the access layer and forward to the core. The aggregation layer in a service provider network collects traffic from the access layer (where customers connect) and aggregates it before sending to the core. It acts as a midpoint, concentrating traffic and applying policies, reducing the number of high-speed links needed in the core.

Answer

Provide direct customer connections

Answer

Perform deep packet inspection

Answer

Provide high-speed backbone connectivity

Question 15

Which MEF Carrier Ethernet service type is used for a rooted-multipoint topology, where a single root site communicates with multiple leaf sites but leaf sites cannot communicate directly?

Accepted Answer

E-Tree. E-Tree (Ethernet Tree) is a rooted-multipoint service where the root can communicate with leaves, but leaves cannot communicate with each other.

Answer

E-Access

Answer

E-LAN

Answer

E-Line