350-501 Architecture Practice Test 10 — 15 Questions

Question 1

A service provider has deployed QoS on its MPLS backbone to offer different classes of service. The provider notices that EF (Expedited Forwarding) traffic sometimes experiences high jitter during congestion. Following recommended practices, which action is MOST likely to reduce jitter for EF traffic?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Use priority queuing (LLQ) for EF traffic with a policer. Priority queuing (LLQ) with a policer ensures EF traffic is served strictly before other queues, reducing jitter, while the policer prevents EF traffic from monopolizing bandwidth. Option B is wrong because traffic shaping smooths bursts but does not provide priority treatment during congestion, so jitter can still occur. Option C is wrong because changing DSCP to AF41 would reclassify EF traffic to a lower priority class, potentially increasing jitter and delay. Option D is wrong because WRED is a congestion avoidance mechanism that drops packets randomly, which can cause jitter for EF traffic; EF should be exempt from WRED.

Answer

Apply traffic shaping on all EF packets at the edge

Answer

Change the DSCP value of EF traffic to AF41 to reduce drops

Answer

Apply weighted random early detection (WRED) on the EF queue

Question 2

A multicast service provider is designing an IPv4 PIM Sparse Mode (PIM-SM) network with multiple RPs. The network must support Anycast RP using MSDP. Which THREE statements are correct regarding this design?

Accepted Answer

Anycast RP allows multiple RPs to share the same IP address, providing redundancy and load balancing. Options A, C, and E are correct. Option A: Anycast RP uses the same IP address on multiple RPs, providing redundancy and load balancing. Option C: MSDP peering is required between the anycast RPs to exchange active source information. Option E: IGMPv3 is needed on last-hop routers to support Source-Specific Multicast (SSM) if used together with Anycast RP. Option B is incorrect: Auto-RP is not required; Anycast RP can work with static RP assignments. Option D is incorrect: MSDP is used for Anycast RP, not specifically for SSM; SSM does not require MSDP.

Answer

Auto-RP must be used to distribute the RP information to all routers

Answer

MSDP is only required if the network uses Source-Specific Multicast (SSM)

Question 3

Based on the exhibit, why is the route 10.10.10.0/24 from remote PE not installed in the VRF Customer-A on PE1?

Accepted Answer

The VRF imports route-target 200:200, but the route has RT 100:100. The route has RT 100:100, but VRF Customer-A imports RT 200:200. Thus, the route is not imported. Option A is wrong because the localpref is 100, which is default and not an issue. Option C is wrong because the RD mismatch is between VRFs, but RD does not affect import; RT does. Option D is wrong because label allocation is working fine (vpn-label:24000).

Answer

The localpref is too low (100)

Answer

The MPLS label allocation failed on the remote PE

Answer

The route distinguisher on the VRF (100:1) does not match the remote RD

Question 4

A service provider operates an MPLS-TE network using RSVP-TE with a full mesh of tunnels between core routers. The network uses OSPF as IGP with traffic engineering extensions. Recently, a new headend router PE-New was added and configured with several TE tunnels to remote destinations. However, some tunnels repeatedly go down after a few minutes and show in the 'down' state with the error 'Tunnel path option 0: no path to destination (TEDB lookup failed)'. The TE tunnels that remain up are those to destinations that are directly connected to the same OSPF area. The network has multiple OSPF areas (area 0, 1, 2) with inter-area routes redistributed. The operator suspects the issue is related to the TEDB (Traffic Engineering Database) not having complete information. Which action is MOST likely to resolve the issue?

Accepted Answer

Change the IGP to IS-IS with wide metrics and enable MPLS-TE on all IS-IS levels. The issue is that OSPF does not flood traffic engineering (TE) information across area boundaries by default. The TEDB on PE-New lacks topology data for inter-area destinations, so tunnel path computation fails. IS-IS, when configured with wide metrics and MPLS-TE enabled on all levels, floods TE link-state information throughout the entire routing domain (both Level-1 and Level-2), ensuring the TEDB is complete. This resolves the problem. Option D (static routes) does not populate the TEDB. Option B does not help because adding loopbacks to OSPF does not provide TE information. Option A (priorities) only affects tunnel setup and preemption, not TEDB completeness.

Answer

Increase the tunnel hold-priority and setup-priority values

Answer

Add the remote loopbacks to OSPF using network statements in area 0

Answer

Configure static routes for the remote destinations on PE-New

Question 5

Which access technology is commonly used in service provider networks to deliver high-speed internet over existing telephone lines?

Accepted Answer

DSL. DSL (Digital Subscriber Line) uses existing telephone lines to provide high-speed internet access.

Answer

Metro Ethernet

Answer

GPON

Answer

Cable

Question 6

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

Accepted Answer

It provides isolation for routing protocols and forwarding tables.. An SDR provides a logical partitioning of router resources, allowing multiple independent virtual routers within a single physical chassis.

Answer

It handles all packet forwarding in hardware.

Answer

It is used for OSPF only.

Answer

It manages the admin plane for all line cards.

Question 7

A service provider is deploying L3VPN using BGP/MPLS. Which mechanism ensures customer isolation in the provider network?

Accepted Answer

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

Answer

Pseudowire

Answer

MP-BGP

Answer

MPLS labels

Question 8

Which Cisco router platform is designed for high-density 100GE and uses IOS XR, making it suitable for the core/backbone of a service provider network?

Accepted Answer

Cisco CRS. Cisco CRS (Carrier Routing System) is a high-end core router supporting high-density 100GE and running IOS XR.

Answer

Cisco NCS 5500

Answer

Cisco ASR 9000

Answer

Cisco ISR 4400

Question 9

In IOS XR, what is the commit/rollback configuration model?

Accepted Answer

Configuration changes are staged and committed atomically; rollback is supported.. The commit/rollback model applies changes atomically and allows reverting to previous configurations if needed.

Answer

It requires a reboot to apply changes.

Answer

Changes are applied immediately and cannot be undone.

Answer

It only applies to interface configurations.

Question 10

A service provider wants to provide point-to-point Ethernet services with strict SLAs. Which technology should they use?

Accepted Answer

VPWS. VPWS (Virtual Private Wire Service) or pseudowire provides a point-to-point Ethernet connection over MPLS.

Answer

EVPN

Answer

L3VPN

Answer

VPLS

Question 11

Which MEF service type provides a point-to-point Ethernet connection between two user-network interfaces (UNIs)?

Accepted Answer

E-Line. E-Line is the MEF service for point-to-point Ethernet connectivity.

Answer

E-LAN

Answer

E-Tree

Answer

E-Access

Question 12

What is the main benefit of using Q-in-Q (802.1ad) in metro Ethernet networks?

Accepted Answer

Increases the number of available VLANs. Q-in-Q allows multiple customer VLANs to be encapsulated within a service provider VLAN, increasing scalability.

Answer

Simplifies routing

Answer

Provides encryption

Answer

Reduces latency

Question 13

In EVPN, what is the function of the Ethernet Segment Identifier (ESI)?

Accepted Answer

It identifies a multi-homed device or network segment.. The ESI identifies a multi-homed device or network, enabling all-active redundancy and fast convergence.

Answer

It is used for load balancing among PEs.

Answer

It uniquely identifies a customer MAC address.

Answer

It identifies a VXLAN tunnel.

Question 14

A service provider is deploying network slicing for 5G services. Which slice type is characterized by low latency and high reliability for applications like autonomous driving?

Accepted Answer

uRLLC. uRLLC (Ultra-Reliable Low-Latency Communications) is designed for latency-critical and reliable applications.

Answer

FMC

Answer

eMBB

Answer

mMTC

Question 15

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

Accepted Answer

confd. The configuration management process handles commit/rollback and stores configuration in a database.

Answer

fman

Answer

sysmgr

Answer

rib