350-501 Architecture Practice Test 16 — 15 Questions

Question 1

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

Accepted Answer

MAC address learning over the control plane (MAC mobility). Option A is correct because EVPN distributes MAC reachability information through BGP control-plane advertisements (MAC/IP Advertisement routes), enabling control-plane MAC learning and MAC mobility, unlike VPLS which relies on data-plane flooding and learning. Option B is correct because EVPN uses MP-BGP as its control plane to distribute MAC and IP routes (and VXLAN/NVGRE or MPLS encapsulation information) via EVPN route types, providing scalable, policy-driven signaling that VPLS lacks. Option C is correct because EVPN supports all-active multihoming through Ethernet Segment Identifiers (ESI) and DF election, allowing a CE to connect to multiple PEs with load balancing and fast failover, whereas VPLS typically only supports single-active or active/standby multihoming. Option D is incorrect because EVPN actually requires BGP (MP-BGP with the EVPN address family), so it is not simpler in that sense. Option E is incorrect because EVPN does not inherently provide lower latency via MPLS label switching; latency depends on the underlying transport, and EVPN can run over VXLAN or MPLS alike.

Answer

Simpler configuration without BGP

Answer

Lower latency due to MPLS label switching

Question 2

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

Accepted Answer

Distributed OS with process separation. Option C is correct because IOS XR is built as a distributed operating system in which processes are isolated from one another, so a failure in one process (for example, a routing protocol) cannot crash the entire system, and components can run on different line cards or nodes. Option E is correct because IOS XR uses a commit-based configuration model in which changes are staged in a target configuration, validated, and only applied when the administrator issues the commit command, with the ability to roll back to a previous committed configuration. The unmarked options do not belong: A is wrong because IOS XR validates configuration before applying it rather than applying changes immediately without validation; B is wrong because IOS XR is not a monolithic kernel with a shared memory address space but rather a modular, memory-protected, distributed architecture; and D is wrong because IOS XR does not run all routing protocols in a single process but instead separates them into individual, independently restartable processes.

Answer

Configuration applied immediately without validation

Answer

Monolithic kernel with shared memory address space

Answer

Single process for all routing protocols

Question 3

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

Accepted Answer

E-LAN. The three MEF-defined Ethernet service types are E-Line, E-Tree, and E-LAN. E-Line (option E) is correct because MEF defines it as a point-to-point Ethernet Virtual Connection (EVC) service, typically used for dedicated point-to-point connectivity such as Ethernet Private Line (EPL) or Ethernet Virtual Private Line (EVPL). E-LAN (option A) is correct because MEF defines it as a multipoint-to-multipoint EVC service, allowing any-to-any connectivity among multiple subscriber sites, as in Ethernet Private LAN (EP-LAN) or Ethernet Virtual Private LAN (EVP-LAN). E-Tree (option D) is correct because MEF defines it as a rooted-multipoint EVC service with one or more root nodes and multiple leaf nodes, where leaves can communicate only with roots, not with each other. The remaining options are not MEF service types: E-Access (option B) is not a MEF-defined Ethernet service type (MEF does define an Access EPL/Access EVPL service, but not 'E-Access'), and E-WAN (option C) is not a MEF service type at all.

Answer

E-Access

Answer

E-WAN

Question 4

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) double tagging encapsulates each customer's 802.1Q VLAN tag inside an additional service-provider VLAN tag, allowing multiple customers to reuse the same VLAN IDs across a shared physical link without conflict. The outer S-VLAN tag identifies the customer or service instance, while the inner C-VLAN tag preserves the customer's own VLAN scheme. This is the standard metro Ethernet access-layer solution for transparent VLAN multiplexing.

Answer

VLAN translation

Answer

MAC-in-MAC (802.1ah)

Answer

VLAN trunking with 802.1Q

Question 5

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 6

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

Accepted Answer

NETCONF. Cisco NSO (Network Services Orchestrator) uses NETCONF as its primary southbound protocol to configure network devices, leveraging YANG data models for structured, transactional configuration. NETCONF's candidate/commit model aligns with NSO's intent-based automation approach.

Answer

CLI scripting

Answer

SNMP

Answer

RESTCONF

Question 7

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 the MPLS-based Layer 2 service that provides point-to-point Ethernet connectivity, emulating a physical wire between two customer sites. It is defined by MEF as E-Line and is implemented in MPLS networks using pseudowires (typically LDP-signaled or BGP-signaled) to carry Ethernet frames across the provider core.

Answer

L3VPN

Answer

VPLS

Answer

EVPN

Question 8

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. SR-MPLS is the Segment Routing data plane that operates directly on MPLS forwarding, allowing a service provider to migrate from LDP to SR without maintaining LDP sessions. It uses MPLS labels to encode segments and can interoperate with existing MPLS infrastructure, making it the appropriate choice for MPLS forwarding without LDP.

Answer

SRv6

Answer

LDP over RSVP

Answer

MPLS-TE with RSVP-TE

Question 9

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). In IOS XR's multi-plane architecture, the admin plane is the management and control layer that owns the configuration and supervision of Secure Domain Routers (SDRs), including creating, starting, and stopping them. It is separate from the routing and forwarding planes that operate within each 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 10

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

Accepted Answer

E-LAN. MEF defines E-LAN as the multipoint-to-multipoint Ethernet virtual connection service, allowing any-to-any communication among multiple customer sites. It is typically implemented using VPLS or EVPN in the provider network and is analogous to a virtual Ethernet LAN spanning sites.

Answer

E-Access

Answer

E-Line

Answer

E-Tree

Question 11

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

Accepted Answer

MPLS label switching. P routers in an MPLS core are label-switching routers (LSRs) that forward packets based solely on the incoming MPLS label, swapping it for the outgoing label learned via LDP or RSVP-TE. They do not run the customer VPN context and never look at the inner IP header, which is why L3VPN scales — the P router only needs the IGP plus label bindings. This label-swap-and-forward behavior is the definition of MPLS label switching.

Answer

MPLS label imposition

Answer

MPLS label disposition

Answer

IP routing based on destination IP

Question 12

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

Accepted Answer

Each routing protocol runs as an independent process in IOS XR.. Option C is correct because IOS XR uses a microkernel-based, modular architecture in which each routing protocol (for example BGP, OSPF, and ISIS) runs as its own independent, memory-protected process, so a failure or restart of one protocol does not crash the others. Option E is correct because IOS XR uses a two-stage configuration model: changes are made in a target configuration and only applied with the commit command, and the system retains rollback points so you can revert to a previous committed configuration with commands such as rollback configuration or show configuration commit list. Option A is wrong because IOS XR does not apply configuration changes immediately; uncommitted changes stay in the target configuration until an explicit commit is issued. Option B is wrong because the admin plane in IOS XR is a separate, secure management space used for system administration and control-plane tasks, not for customer VPN configuration, which belongs in the shared or user plane. Option D is wrong because IOS XR is not a monolithic kernel with shared memory; its defining characteristic is a modular, microkernel-based design with isolated processes.

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 13

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

Accepted Answer

Supports all-active multi-homing. EVPN supports all-active multi-homing (Option B), meaning a CE device can connect to multiple PEs that all forward traffic simultaneously, providing load balancing and faster convergence than traditional active/standby multi-homing. It also supports multi-homing with an Ethernet Segment Identifier (Option C), where the ESI uniquely identifies the Ethernet segment across the participating PEs so they can coordinate DF election and aliasing. EVPN uses BGP as its control plane signaling protocol (Option D), specifically MP-BGP with EVPN NLRI (AFI 25, SAFI 70) to distribute MAC/IP reachability and IMET routes. Option A is wrong because EVPN provides both L2VPN (E-LAN, E-LINE) and L3VPN services, not only L2VPN. Option E is wrong because EVPN does not use LDP for pseudowire signaling; that is characteristic of VPWS/VPLS using LDP-based signaling, whereas EVPN relies on BGP.

Answer

Provides only L2VPN services

Answer

Uses LDP for pseudowire signaling

Question 14

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

Accepted Answer

Each slice can have its own dedicated bandwidth and latency guarantees.. Option C is correct because network slicing uses SDN, NFV, and orchestration to create logically isolated end-to-end networks, and each slice can be assigned dedicated radio, transport, and core resources with specific SLA-backed bandwidth and latency guarantees. Option D is correct because 5G network slicing is explicitly designed to support differentiated service types, including enhanced Mobile Broadband (eMBB), ultra-Reliable Low-Latency Communications (uRLLC), and massive Machine-Type Communications (mMTC), each with tailored performance characteristics. Option A is incorrect because network slicing spans the RAN, transport, and core domains, not just the 5G core. Option B is incorrect because slices are logical partitions that share a common physical infrastructure rather than requiring separate physical hardware. Option E is incorrect because QoS mechanisms such as 5QI, QFI, and scheduling policies remain essential to enforce each slice's performance guarantees.

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 15

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