350-501 Architecture Practice Test 14 — 15 Questions

Question 1

A metro Ethernet provider needs to scale customer VLANs beyond the 4,096 limit by encapsulating customer VLAN tags with an outer service provider tag. Which IEEE standard is used?

Accepted Answer

802.1ad (Q-in-Q). Q-in-Q (802.1ad) adds an outer VLAN tag to extend VLAN space. 802.1ah is for MAC-in-MAC, 802.1Q is the basic standard, and 802.1ak is not related.

Answer

802.1ah (Provider Backbone Bridging)

Answer

802.1Q

Answer

802.1ak

Question 2

Which statement about the commit/rollback configuration model in IOS XR is true?

Accepted Answer

If a commit fails, the system automatically rolls back to the last committed configuration. IOS XR uses a two-phase commit: the user commits, and if successful, the configuration is applied; otherwise, it rolls back. There is no need for explicit rollback commands.

Answer

Rollback requires manual deletion of uncommitted changes

Answer

Configuration is applied to all cards simultaneously without validation

Answer

Changes take effect immediately without a commit command

Question 3

Which technology provides Layer 2 multipoint connectivity over an MPLS network, where customer sites appear to be on the same Ethernet broadcast domain?

Accepted Answer

VPLS. VPLS (Virtual Private LAN Service) emulates a multipoint Ethernet LAN over MPLS. VPWS is point-to-point, EVPN is modern but not always broadcast, and L3VPN is layer 3.

Answer

L3VPN

Answer

VPWS (Virtual Private Wire Service)

Answer

EVPN

Question 4

Which Cisco router platform is designed for the aggregation layer and runs IOS XR, supporting both L2 and L3 services at high density?

Accepted Answer

Cisco ASR 9000. The ASR 9000 is a widely used aggregation router with IOS XR and supports L2/L3 services. CRS is core, NCS 5500 is edge/aggregation but more focused on 100GE, and ISR is enterprise.

Answer

Cisco NCS 5500

Answer

Cisco CRS

Answer

Cisco ISR 4000

Question 5

In an IOS XR system, CPU and memory resources are allocated per line card. What is the primary reason for this design?

Accepted Answer

To ensure that a failure on one card does not impact others. Distributed architecture with per-card allocation improves scalability and fault isolation. It does not directly reduce cost or simplify management; instead, it enhances performance and resilience.

Answer

To reduce hardware cost by sharing resources

Answer

To simplify software licensing

Answer

To centralize management in the route processor

Question 6

Which TWO statements accurately describe the differences between GPON and XGS-PON? (Choose two.)

Accepted Answer

XGS-PON uses passive optical splitters.. XGS-PON provides symmetric 10 Gbps, while GPON is asymmetric (2.5G/1.25G). Both use passive optical splitters and WDM.

Answer

GPON offers higher downstream bandwidth than XGS-PON.

Answer

GPON requires active amplification in the field.

Answer

GPON uses WDM while XGS-PON does not.

Question 7

Which THREE are benefits of using EVPN over traditional VPLS? (Choose three.)

Accepted Answer

MAC address learning over the control plane (MAC mobility). EVPN offers BGP-based control plane, multi-homing support, and MAC mobility. VPLS traditionally uses LDP and does not natively support multi-homing or MAC mobility as effectively.

Answer

Simpler configuration without BGP

Answer

Lower latency due to MPLS label switching

Question 8

Which TWO are key features of IOS XR architecture? (Choose two.)

Accepted Answer

Distributed OS with process separation. IOS XR is a distributed OS with process separation and a commit/rollback model. Monolithic kernel and shared memory are not features.

Answer

Configuration applied immediately without validation

Answer

Monolithic kernel with shared memory address space

Answer

Single process for all routing protocols

Question 9

Which THREE are MEF-defined Ethernet service types? (Choose three.)

Accepted Answer

E-LAN. MEF defines E-Line, E-LAN, and E-Tree. E-Access is also defined but is not part of the three main types. E-WAN is not a standard MEF service.

Answer

E-Access

Answer

E-WAN

Question 10

A service provider is deploying a new metro Ethernet network and needs to support multiple customer VLANs over a single physical link without overlapping VLAN IDs. Which technology should be used at the access layer to achieve this?

Accepted Answer

Q-in-Q (802.1ad) double tagging. Q-in-Q (802.1ad) allows service providers to add an outer VLAN tag to customer frames, enabling customer VLAN separation even when their VLAN IDs conflict. This is commonly used in metro Ethernet networks for scalability.

Answer

VLAN translation

Answer

MAC-in-MAC (802.1ah)

Answer

VLAN trunking with 802.1Q

Question 11

An SP is designing a core network using Cisco CRS routers running IOS XR. They require process separation to ensure that a failure in the BGP process does not affect OSPF operations. Which IOS XR architectural feature provides this capability?

Accepted Answer

Process separation. IOS XR uses a distributed OS where each protocol runs as a separate process (process separation). This prevents a crash in one protocol process from impacting others, enhancing stability.

Answer

Non-Stop Forwarding (NSF)

Answer

Graceful Restart

Answer

Secure Domain Router (SDR)

Question 12

Which Cisco router platform is designed for the aggregation layer and supports both mobile backhaul and business services with high density 10GE/100GE interfaces?

Accepted Answer

Cisco NCS. Cisco NCS (Network Convergence System) routers are designed for the aggregation layer, offering high port density and support for various services including mobile backhaul and business connectivity.

Answer

Cisco ASR 9000

Answer

Cisco CRS

Answer

Cisco ISR 4000

Question 13

A provider is implementing EVPN for data center interconnect. They require multi-homing with all-active load balancing and fast convergence using BGP. Which EVPN feature enables this?

Accepted Answer

Ethernet Segment Identifier (ESI). EVPN uses Ethernet Segment Identifier (ESI) for multi-homing. All-active mode allows load balancing across multiple PE nodes, and BGP control plane provides fast convergence via route withdrawal.

Answer

MPLS Traffic Engineering

Answer

BGP Link-State

Answer

VPLS with BGP autodiscovery

Question 14

An SP is deploying network slicing for 5G services. They need to ensure ultra-reliable low-latency communication (uRLLC) slice has dedicated bandwidth and low latency. Which mechanism is best suited to guarantee performance for this slice?

Accepted Answer

Flexible Algorithm (Flex-Algo) in IGP. Network slicing using dedicated resources via Flex-Algo or resource reservation can guarantee performance. Flex-Algo allows IGP to compute paths based on constraints like latency, providing dedicated paths for uRLLC.

Answer

Class of Service (CoS) marking on all traffic

Answer

MPLS Traffic Engineering with RSVP-TE

Answer

DiffServ with EF PHB

Question 15

A service provider wants to automate service provisioning using NSO. Which protocol is typically used by NSO to configure network devices?

Accepted Answer

NETCONF. NSO uses NETCONF as the primary protocol for device configuration, leveraging YANG models for service modeling.

Answer

CLI scripting

Answer

SNMP

Answer

RESTCONF