350-501 Architecture Practice Test 15 — 15 Questions

Question 1

Which MPLS-based service provides point-to-point Ethernet connectivity over a service provider network, emulating a wire?

Accepted Answer

VPWS. VPWS (Virtual Private Wire Service) is a pseudowire that provides point-to-point L2VPN connectivity, emulating a physical wire.

Answer

L3VPN

Answer

VPLS

Answer

EVPN

Question 2

An SP is using Cisco ASR 9000 routers with IOS XR. They need to apply a configuration change and ensure that if the change causes issues, it can be easily reverted. Which IOS XR feature supports this?

Accepted Answer

Commit/rollback. IOS XR uses a commit/rollback configuration model. Changes are staged in a candidate configuration and committed; if issues arise, rollback to a previous commit is possible.

Answer

Configuration replace

Answer

Synchronization to standby

Answer

Archive and restore

Question 3

A service provider is migrating from LDP to Segment Routing (SR) in the core. They need to support MPLS forwarding without maintaining LDP sessions. Which SR data plane is appropriate?

Accepted Answer

SR-MPLS. Segment Routing with MPLS data plane (SR-MPLS) uses IGP to distribute labels, eliminating the need for LDP. SR-MPLS is the direct replacement for LDP in MPLS networks.

Answer

SRv6

Answer

LDP over RSVP

Answer

MPLS-TE with RSVP-TE

Question 4

What is the function of the admin plane in IOS XR architecture?

Accepted Answer

It provides a management interface for configuring Secure Domain Routers (SDRs). The admin plane is a separate management context for administrative tasks such as configuring SDRs, managing hardware, and system-level settings. It provides isolation from the default SDR.

Answer

It runs routing protocols for the default SDR

Answer

It handles data plane forwarding

Answer

It is used for customer-facing VPN services

Question 5

Which MEF service type provides a multipoint-to-multipoint Ethernet virtual connection?

Accepted Answer

E-LAN. E-LAN (Ethernet LAN) service provides multipoint-to-multipoint connectivity, as per MEF standards.

Answer

E-Access

Answer

E-Line

Answer

E-Tree

Question 6

A service provider is deploying L3VPN. Which mechanism ensures that customer routes are isolated and not leaked between different customers?

Accepted Answer

VRF. VRF (Virtual Routing and Forwarding) instances provide separate routing tables per customer, ensuring isolation in L3VPN.

Answer

Route target (RT)

Answer

Route distinguisher (RD)

Answer

MPLS labels

Question 7

An SP is designing a GPON access network. Which technology allows multiple ONUs to share the same fiber using different wavelengths for upstream and downstream?

Accepted Answer

Wavelength Division Multiplexing (WDM). GPON uses Wavelength Division Multiplexing (WDM) with different wavelengths for downstream (1490nm) and upstream (1310nm) on the same fiber.

Answer

Ethernet PON (EPON)

Answer

Time Division Multiple Access (TDMA)

Answer

Code Division Multiple Access (CDMA)

Question 8

In an MPLS core, which forwarding mechanism do P routers use to forward packets for L3VPN?

Accepted Answer

MPLS label switching. P routers (core routers) perform label switching based on the MPLS label stack. They do not need to examine the IP header; they swap labels and forward accordingly.

Answer

MPLS label imposition

Answer

MPLS label disposition

Answer

IP routing based on destination IP

Question 9

Which Cisco platform is designed for high-capacity core/backbone routing with support for MPLS, Segment Routing, and large-scale BGP?

Accepted Answer

Cisco CRS. Cisco CRS (Carrier Routing System) is a high-end core router designed for large service provider backbone networks, supporting MPLS, SR, and massive scale.

Answer

Cisco NCS 5500

Answer

Cisco 8000 series

Answer

Cisco ASR 9000

Question 10

Which TWO statements about IOS XR architecture are correct? (Choose two.)

Accepted Answer

Each routing protocol runs as an independent process in IOS XR.. IOS XR uses distributed OS with process separation, and a commit/rollback model for configuration. It does not have a monolithic kernel; each protocol is a separate process. The admin plane is separate from SDRs.

Answer

Configuration changes in IOS XR take effect immediately without a commit.

Answer

The admin plane in IOS XR is used for customer VPN configuration.

Answer

IOS XR runs a monolithic kernel where all protocols share the same memory space.

Question 11

Which THREE are characteristics of EVPN? (Choose three.)

Accepted Answer

Supports all-active multi-homing. EVPN uses BGP control plane, supports multi-homing with ESI, and can provide both L2 and L3 services. It does not use LDP for signaling; it uses BGP. VPLS is older.

Answer

Provides only L2VPN services

Answer

Uses LDP for pseudowire signaling

Question 12

Which TWO are correct about network slicing? (Choose two.)

Accepted Answer

Each slice can have its own dedicated bandwidth and latency guarantees.. Network slicing divides a physical network into multiple virtual networks, each with dedicated resources. Slices can be tailored for specific services like eMBB, uRLLC, mMTC. They are not limited to 5G core but also include transport.

Answer

Network slicing is only applicable to the 5G core network.

Answer

Network slicing requires a separate physical infrastructure for each slice.

Answer

Network slicing eliminates the need for QoS mechanisms.

Question 13

In a service provider network, the access layer connects end customers. Which technology is commonly used for fibre-based access in GPON deployments?

Accepted Answer

GPON. GPON (Gigabit Passive Optical Network) is a fibre-based access technology standardized by ITU-T.

Answer

DSL

Answer

MPLS

Answer

Metro Ethernet

Question 14

Which Cisco SP router platform runs IOS XR and is designed for the aggregation layer with high-density 10GE/100GE interfaces?

Accepted Answer

Cisco ASR 9000. The Cisco ASR 9000 series is optimized for the aggregation layer with dense 10GE/100GE ports and runs IOS XR.

Answer

Cisco ISR 4000

Answer

Cisco CRS

Answer

Cisco NCS 5500

Question 15

In IOS XR architecture, what is the purpose of Secure Domain Router (SDR)?

Accepted Answer

To enable process separation and fault isolation. SDR logically partitions a physical router into multiple independent routers, each with its own control plane and resources.

Answer

To encrypt control plane traffic

Answer

To provide a secure management plane

Answer

To aggregate multiple physical routers