350-501 Architecture Practice Test 3 — 15 Questions

Question 1

In an MPLS-based service provider core network, the aggregation layer typically connects to the core backbone. Which technology is primarily used at the aggregation layer to scale Ethernet services for many customers while preserving VLAN separation?

Accepted Answer

Q-in-Q (IEEE 802.1ad). Q-in-Q (802.1ad) allows service providers to stack a customer VLAN tag on top of a service VLAN tag, enabling scalable customer separation in metro Ethernet networks.

Answer

IEEE 802.1ah (MAC-in-MAC)

Answer

IEEE 802.3ad (Link Aggregation)

Answer

IEEE 802.1x (Port-based Network Access Control)

Question 2

A service provider wants to provide a point-to-point Ethernet service between two customer sites with strict Service Level Agreements (SLAs). Which MEF service type should be used?

Accepted Answer

E-Line. E-Line is a MEF standard for point-to-point Ethernet services, providing dedicated bandwidth and SLA guarantees.

Answer

E-LAN

Answer

E-Access

Answer

E-Tree

Question 3

In Cisco IOS XR architecture, using Secure Domain Routers (SDRs) allows partitioning a physical router into multiple logical routers. Which statement about admin plane and SDRs is correct?

Accepted Answer

The admin plane is a separate SDR that manages hardware resources and system-level functions, while the default SDR handles routing and forwarding.. The admin plane is a special SDR used for managing the system (e.g., hardware inventory, shared resources). Default SDR is the primary forwarding SDR, but admin SDR is separate.

Answer

The admin plane runs only on route processor cards, while default SDR runs on line cards.

Answer

The admin plane and default SDR are the same logical entity and share all configuration.

Answer

SDRs are only supported on Cisco CRS, not on ASR 9000.

Question 4

Which access technology uses a passive optical splitter to deliver broadband services to multiple subscribers over a single fiber?

Accepted Answer

GPON. GPON (Gigabit Passive Optical Network) uses passive splitters to share fiber among multiple subscribers.

Answer

Cable (DOCSIS)

Answer

Metro Ethernet

Answer

DSL (Digital Subscriber Line)

Question 5

An SP is deploying EVPN to provide both L2 and L3 VPN services. Which advantage does EVPN offer over traditional VPLS for multi-homing?

Accepted Answer

EVPN provides faster convergence and active-active multi-homing using Ethernet Segment Identifier (ESI) and Designated Forwarder (DF) election.. EVPN uses ESI-based multi-homing with BGP control plane, offering faster convergence and active-active load balancing compared to VPLS's active/standby model.

Answer

EVPN uses a single MAC address per PE to reduce forwarding table size.

Answer

EVPN supports only active/standby redundancy, similar to VPLS.

Answer

EVPN requires MPLS in the core, whereas VPLS can use IP-only.

Question 6

Which Cisco platform is best suited for the core/backbone role of a large service provider network, offering high scalability and MPLS forwarding capacity?

Accepted Answer

Cisco CRS. Cisco CRS (Carrier Routing System) is designed for the core with high capacity and MPLS capabilities.

Answer

Cisco ASR 1000

Answer

Cisco ASR 9000

Answer

Cisco NCS 5500

Question 7

In IOS XR, each routing protocol runs as a separate process. What is the primary benefit of this architecture?

Accepted Answer

It allows each protocol to be upgraded independently without a system reboot.. Process separation provides fault isolation; a crash in one protocol process does not affect others, improving overall system stability.

Answer

It simplifies configuration by combining all protocols into a single file.

Answer

It reduces memory consumption by sharing code between processes.

Answer

It improves forwarding performance by dedicating CPU cores to each protocol.

Question 8

Which MEF service type is used for multipoint-to-multipoint Ethernet connectivity, such as a corporate LAN extension across multiple sites?

Accepted Answer

E-LAN. E-LAN provides multipoint-to-multipoint connectivity, emulating a LAN across multiple locations.

Answer

E-Line

Answer

E-Tree

Answer

E-Access

Question 9

A service provider is implementing network slicing for 5G services. Which of the following is NOT a typical characteristic of a network slice?

Accepted Answer

Slices require dedicated physical infrastructure per slice.. Network slices are isolated virtual networks, but they share the same physical infrastructure; they do not have dedicated physical links.

Answer

Each slice can have its own dedicated virtualized functions and resources.

Answer

Slices can be customized for specific service types like eMBB, uRLLC, or mMTC.

Answer

Slices are isolated from each other in terms of performance and security.

Question 10

In the context of IOS XR commit/rollback configuration model, which command is used to apply a set of configuration changes as a single atomic operation?

Accepted Answer

commit. The 'commit' command applies changes atomically; if any part fails, the entire commit is rejected.

Answer

save config

Answer

apply-changes

Answer

copy running-config startup-config

Question 11

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 12

In BGP/MPLS IP VPN (L3VPN), which component provides customer isolation by maintaining separate routing tables per customer?

Accepted Answer

VRF. VRF (Virtual Routing and Forwarding) creates separate routing tables for each customer, ensuring isolation.

Answer

Route distinguisher (RD)

Answer

MPLS label

Answer

MP-BGP

Question 13

An SP is designing a metro Ethernet network using Q-in-Q. A customer uses VLAN ID 100 on their network, and the SP assigns service VLAN 200. Which frame format is used on the SP network?

Accepted Answer

Double tag: outer 200, inner 100. Q-in-Q adds an outer (service) VLAN tag (200) while preserving the inner (customer) VLAN tag (100).

Answer

Single tag: VLAN 100

Answer

Double tag: outer 100, inner 200

Answer

Single tag: VLAN 200

Question 14

Which Cisco SP router platform uses IOS XR and is commonly deployed at the aggregation layer, supporting both L2 and L3 services?

Accepted Answer

Cisco ASR 9000. Cisco ASR 9000 is an aggregation router running IOS XR, suitable for L2/L3 services.

Answer

Cisco CRS

Answer

Cisco ASR 1000

Answer

Cisco NCS 540

Question 15

Which access technology is based on ITU-T G.984 and provides downstream speeds up to 2.488 Gbps?

Accepted Answer

GPON. GPON (Gigabit-PON) is defined by ITU-T G.984 with downstream up to 2.488 Gbps.

Answer

XGS-PON

Answer

DSL

Answer

EPON