350-501 Practice Test 30 — 15 Questions

Question 1

Refer to the exhibit. Which statement is true regarding the forwarding entry for 10.2.2.0/24?

Accepted Answer

This entry uses explicit label request (not PHP).. Option A is correct because the forwarding entry for 10.2.2.0/24 shows an outgoing label of 20, which means the egress LSR is not performing penultimate hop popping (PHP). In MPLS, when the outgoing label is not the implicit-null label (3) or explicit-null label (0), the penultimate hop must push that label, and the egress LSR will perform a full label lookup. This is an explicit label request, not PHP.

Answer

The outgoing interface uses penultimate hop popping.

Answer

The outgoing label is Untagged.

Answer

The local label is 20.

Question 2

When implementing MPLS TE tunnels in a service provider core, what is the purpose of the 'affinity' attribute?

Accepted Answer

To define administrative groups for link inclusion/exclusion. The 'affinity' attribute in MPLS TE is used to define administrative groups (also known as link colors) that allow you to include or exclude specific links from a TE tunnel path based on user-defined properties. This enables traffic engineering policies such as forcing traffic to avoid certain links or preferring links with specific characteristics, without modifying the underlying IGP metric.

Answer

To set the color of the tunnel

Answer

To adjust the cost of TE tunnels

Answer

To bind tunnels to specific interfaces

Question 3

Which THREE are common causes of QoS misconfiguration on PE routers? (Choose three.)

Accepted Answer

Applying a policy-map in the wrong direction (input vs output).. Applying a policy-map in the wrong direction (input vs output) is a common QoS misconfiguration because QoS actions like shaping, policing, and queuing are direction-specific. For example, shaping is typically applied on the egress interface to control outbound traffic, while policing can be applied inbound to rate-limit incoming traffic. Misapplying a policy-map (e.g., attaching a shaper to the input direction) will either be ignored by the router or cause unexpected behavior, leading to QoS failures.

Answer

Using the 'bandwidth percent' command in a class that also has a priority queue.

Answer

Insufficient bandwidth on the subscriber line.

Question 4

Which THREE of the following are required for successful operation of OSPFv3 in an IPv6 service provider network?

Accepted Answer

Interface activation with 'ipv6 ospf area '. Option A is correct because OSPFv3 requires interface-level activation using the 'ipv6 ospf area ' command to enable the OSPFv3 process on a specific interface and associate it with an area. Without this, the interface will not participate in OSPFv3 neighbor discovery or routing updates, even if the process is configured globally.

Answer

OSPFv3 authentication configured

Answer

OSPFv3 LSA type 9 for link-local addresses

Question 5

A customer is experiencing packet loss during congestion on a link. The service provider wants to implement a QoS policy that drops less important traffic before more important traffic. Which queuing mechanism is best suited?

Accepted Answer

Class-Based Weighted Fair Queuing (CBWFQ) with WRED. CBWFQ with WRED is the best choice because CBWFQ provides per-class queuing with guaranteed bandwidth, while WRED proactively drops less important traffic (based on IP precedence or DSCP) before the queue becomes full, preventing tail drop and ensuring that higher-priority traffic is preserved during congestion. This combination allows the service provider to selectively discard lower-priority packets under congestion, meeting the requirement to drop less important traffic before more important traffic.

Answer

FIFO queuing

Answer

Low Latency Queuing (LLQ)

Answer

Traffic shaping

Question 6

A service provider is using LISP to provide host mobility. Which LISP component is responsible for storing the mapping of EID to RLOC?

Accepted Answer

Map-Server. In LISP (RFC 6830), the Map-Server (MS) is the central repository that stores the mapping of Endpoint Identifiers (EIDs) to Routing Locators (RLOCs). When an Ingress Tunnel Router (ITR) needs to forward traffic to a destination EID, it queries the Map-Resolver, which in turn contacts the Map-Server to retrieve the authoritative mapping. The Map-Server also accepts registration from Egress Tunnel Routers (ETRs) on behalf of their EID prefixes, making it the definitive source for EID-to-RLOC bindings.

Answer

Altitude

Answer

Tunnel Router

Answer

Map-Resolver

Question 7

A SP wants to automate the deployment of QoS policies on numerous PE routers using NETCONF. Which YANG module is most appropriate for modeling the QoS policy-map configuration?

Accepted Answer

Cisco-IOS-XR-qos-ma-cfg. Option B is correct because the Cisco-IOS-XR-qos-ma-cfg YANG module is specifically designed to model QoS policy-map configurations on Cisco IOS XR platforms. Since the SP is using NETCONF to automate QoS policies on PE routers running IOS XR, this native module provides the exact data model for defining class-maps, policy-maps, and service policies, aligning with the task's requirement.

Answer

ietf-interfaces

Answer

Cisco-IOS-XR-ip-tcp-yang

Answer

ietf-netconf-acm

Question 8

Which multicast RP model is recommended for large-scale networks to provide redundancy and load sharing?

Accepted Answer

Anycast-RP. Anycast-RP is recommended for large-scale networks because it allows multiple RPs to share the same IP address, providing redundancy and load sharing without requiring dynamic RP discovery protocols. This model uses MSDP (Multicast Source Discovery Protocol) or PIM (Protocol Independent Multicast) to synchronize multicast state between RPs, ensuring that sources and receivers can register with the nearest RP for optimal path selection.

Answer

Auto-RP

Answer

BSR

Answer

Static RP

Question 9

A network engineer is troubleshooting a BGP convergence issue in a large service provider network. After a link failure in the core, BGP sessions between route reflectors take a long time to reconverge. The RRs are receiving updates from many clients. Which technology can be implemented to improve convergence time? The network currently uses standard BGP with default timers.

Accepted Answer

BGP Add-Path. BGP Add-Path allows a route reflector to advertise multiple paths for the same prefix to its clients, which reduces the need for clients to re-advertise updates after a failure. This speeds up convergence by enabling the route reflector to immediately select and propagate an alternate path without waiting for BGP reconvergence from other clients. In large service provider networks with many clients, this minimizes the delay caused by the route reflector having only a single best path per prefix.

Answer

BGP TCP MD5 authentication

Answer

BGP route-refresh

Answer

BGP next-hop-self

Question 10

A service provider needs to prioritize voice traffic over best-effort data in an MPLS VPN. The PE router uses a QoS policy applied to the ingress interface. Which action ensures that voice packets are marked with the correct DSCP value before entering the MPLS core?

Accepted Answer

Apply a policy-map that matches voice traffic using a class-map and the 'set dscp ef' action.. Option A is correct because the question specifies that the PE router must mark voice packets with the correct DSCP value before they enter the MPLS core. The 'set dscp ef' action in a policy-map applied to the ingress interface explicitly sets the DSCP field to EF (46) for voice traffic matched by a class-map, ensuring proper classification and treatment across the MPLS network. This is the standard method for marking IP packets at the edge before MPLS encapsulation.

Answer

Configure the ingress interface with 'mls qos trust dscp' to preserve the customer marking.

Answer

Use a policy-map with the 'set mpls experimental 5' command.

Answer

Apply a police action to drop traffic exceeding the voice bandwidth.

Question 11

Which THREE YANG data nodes are part of the Cisco-IOS-XR-qos-ma-cfg module for defining a QoS policy-map? (Choose three.)

Accepted Answer

class. Option A is correct because the 'class' YANG data node is defined in the Cisco-IOS-XR-qos-ma-cfg module to specify a traffic class within a QoS policy-map. This node allows you to associate a class-map with the policy, enabling differentiated treatment of traffic based on classification criteria.

Answer

urn:cisco:params:xml:ns:yang:Cisco-IOS-XR-qos-ma-cfg

Answer

interface

Question 12

An SP engineer implements LLQ for VoIP traffic on a DS3 link. The policy-map calls for a priority queue of 500 kbps. The actual VoIP traffic averages 400 kbps with bursts to 600 kbps. What is the expected behavior during bursts?

Accepted Answer

The priority queue drops all traffic above the configured 500 kbps during the burst.. C is correct because the priority queue in a Low Latency Queueing (LLQ) policy is policed at the configured rate (500 kbps). When VoIP traffic bursts exceed this rate, the excess packets are dropped immediately by the policer, not queued or reclassified. This ensures that the priority queue does not starve other queues and maintains low latency for conforming traffic.

Answer

The excess traffic is reclassified to best-effort and placed in the default queue.

Answer

The priority queue uses tail-drop and discards only when the queue is full.

Answer

The excess traffic is queued in the priority queue until bandwidth is available.

Question 13

A network operator deploys a QoS policy on a route reflector to classify traffic based on BGP community values. However, the policy is not matching the intended traffic. Which is the most likely cause?

Accepted Answer

The class-map uses a match statement referencing BGP community values, which are not visible at the QoS classification stage.. BGP community values are exchanged as part of the BGP routing update and are stored in the BGP table, but they are not carried in the IP packet header. QoS classification in Cisco IOS operates on fields within the Layer 2 or Layer 3 packet header (e.g., DSCP, IP precedence, CoS) and cannot inspect BGP attributes like community values. Therefore, a class-map using a match statement for BGP communities will never match traffic at the QoS classification stage, making this the most likely cause of the policy not working.

Answer

The policy-map is applied to the wrong interface.

Answer

The service-policy is applied in the wrong direction (input vs output).

Answer

The class-default class is consuming all traffic.

Question 14

Which TWO are valid benefits of automating QoS policy management in a large SP network? (Choose two.)

Accepted Answer

Reduced human error in configuration.. Option D is correct because automating QoS policy management eliminates manual configuration steps, reducing the risk of syntax errors, misapplied policies, or inconsistent deployments across thousands of devices. Automation tools like Ansible or NSO enforce standardized templates and pre-validated configurations, directly lowering human error rates in large SP networks.

Answer

Eliminates the need for monitoring QoS performance.

Answer

Slower deployment of QoS changes.

Answer

Requires no validation of configurations before apply.

Question 15

Refer to the exhibit. An engineer applies two service policies to the same subinterface in the outbound direction. Which statement describes the expected behavior?

Accepted Answer

Only the SHAKE-1M policy is applied; the CHILD-QOS policy is ignored.. When two service policies are applied to the same subinterface in the same direction, the router only honors the first policy applied; the second policy is ignored. In this case, SHAKE-1M was applied first, so CHILD-QOS is not processed. Cisco IOS does not allow multiple service policies in the same direction on a single interface or subinterface, as each direction can have only one active policy-map.

Answer

The router automatically nests CHILD-QOS inside SHAKE-1M creating hierarchical QoS.

Answer

The router compiles a combined policy that merges classifications.

Answer

Both policies are applied sequentially; traffic is shaped then classified.

350-501 Practice Test 30 — 15 Questions

Exhibit

350-501 Practice Test 30 — 15 Questions

Exhibit