QoS Architecture

A network engineer is configuring QoS on a Cisco Catalyst 9300 switch to prioritize voice traffic. The switch has multiple access ports connected to IP phones and PCs. The engineer applies a policy-map that matches DSCP EF and sets the CoS to 5. However, after testing, the voice packets are not being marked correctly. What is the most likely cause?

Question 3hardmultiple choice

An enterprise is deploying a new VoIP system and wants to ensure voice traffic receives priority over data traffic on a WAN link. The engineer configures a class-map to match RTP traffic using the 'match protocol rtp' command. However, the class-map does not match any packets. What is the most likely reason?

Question 4easymultiple choice

A network engineer is designing a QoS policy for a Cisco router that connects to an MPLS VPN. The service provider expects all traffic to be marked with IP Precedence values. The engineer wants to ensure that voice traffic (DSCP EF) is mapped to IP Precedence 5. What configuration is required on the router to perform this mapping?

Question 5mediummultiple choice

A company is implementing QoS on its campus network. The network engineer configures a policy-map that sets the CoS value for voice traffic to 5 on a switch interface. However, when the traffic reaches the router, the CoS marking is lost. What is the most likely reason?

Question 6hardmultiple choice

A network engineer is troubleshooting voice quality issues on a WAN link. The engineer notices that voice packets are being dropped during congestion. The QoS policy uses LLQ for voice traffic, but the priority queue is not providing the expected bandwidth. What is the most likely cause?

Question 7easymultiple choice

An enterprise is deploying QoS across a network that includes both Cisco and non-Cisco devices. The engineer wants to use a marking scheme that is end-to-end and not stripped at Layer 3 boundaries. Which marking field should the engineer use?

Question 8mediummultiple choice

A network engineer is configuring QoS on a Cisco router to prioritize business-critical applications. The engineer creates a class-map that matches traffic based on the destination IP address and port. However, the class-map does not match the expected traffic. What is the most likely reason?

Question 9hardmultiple choice

A network engineer is configuring QoS on a Cisco switch to ensure that video traffic (DSCP AF41) is not dropped during congestion. The engineer creates a policy-map that sets the queue-limit for the AF41 class. However, the switch is still dropping video packets. What is the most likely cause?

Question 10hardmultiple choice

A network engineer is implementing QoS on a Cisco router that connects to a service provider. The provider uses MPLS and expects the MPLS EXP bits to be set for voice traffic. The engineer configures a policy-map that sets the MPLS EXP to 5. However, the provider reports that the EXP bits are not being set. What is the most likely reason?

Question 11mediummultiple choice

An architect is designing a QoS policy for a campus LAN that must support real-time voice and video traffic alongside mission-critical data. The design must use the DiffServ model with consistent per-hop behavior across all switches. Which approach should the architect choose to ensure that voice traffic receives priority queuing while video traffic is guaranteed bandwidth without starving other classes?

Question 12mediummultiple choice

A network team is designing QoS for a Cisco SD-WAN fabric connecting multiple branch offices to a central data center. The design must ensure that VoIP traffic from branch sites receives priority treatment across the WAN overlay, regardless of the underlying transport (MPLS, Internet, LTE). Which architectural component should the team configure to enforce consistent QoS policies across all WAN edges?

Question 13mediummultiple choice

Study the full virtualization explanation →

An enterprise is deploying a leaf-spine architecture in its data center to support high-bandwidth east-west traffic. The design must include QoS to prioritize storage replication traffic (iSCSI) over backup traffic, while ensuring low latency for real-time applications. Where should the architect apply QoS classification and queuing policies in this topology?

Question 14mediummultiple choice

A company is virtualizing its network functions using NFV on a KVM-based hypervisor. The design must ensure that the virtual router (CSR1000v) can handle high-throughput traffic with minimal latency. Which architectural consideration is most critical for achieving this goal?

Question 15hardmultiple choice

Read the full wireless explanation →

An architect is designing a QoS policy for a Cisco SD-Access fabric. The policy must prioritize voice traffic from wireless clients connected to fabric-enabled access points over other traffic types. The design should use the fabric's built-in capabilities to simplify deployment. Which approach should the architect take?

Question 16hardmultiple choice

A network team is designing QoS for a multi-tenant data center using leaf-spine architecture. Each tenant requires guaranteed bandwidth for their mission-critical applications, while best-effort traffic must not interfere. The design must use hierarchical queuing to enforce per-tenant fairness. Which queuing mechanism should the architect implement on the leaf switches?

Question 17mediummultiple choice

An enterprise is designing a QoS architecture for its WAN edge routers connecting to multiple service providers. The design must support traffic shaping to avoid packet drops due to provider policers, while also prioritizing real-time traffic. Which approach should the architect use to shape traffic to the contracted CIR while still allowing bursts?

Question 18mediummultiple choice

A network architect is designing QoS for a Cisco SD-WAN deployment that uses a mix of MPLS and broadband Internet transports. The design must ensure that interactive video traffic is not delayed by large file transfers, even when the Internet link experiences congestion. Which SD-WAN policy type should the architect use to enforce this behavior?

Question 19mediummultiple choice

A company is deploying a new campus network with a hierarchical design (core, distribution, access). The QoS design must ensure that voice traffic is prioritized end-to-end, and that marking is trusted only on access ports connected to IP phones. Which architectural approach should the architect take for classification and marking?

Question 20mediummultiple choice

Consider the following configuration snippet:

policy-map QOS_POLICY

class VOICE

priority percent 30

class VIDEO

bandwidth percent 20 queue-limit 50 packets

class class-default

fair-queue queue-limit 100 packets

What is the effect of this configuration?

Question 21mediummultiple choice

Given the following configuration:

interface GigabitEthernet0/1

service-policy output QOS_POLICY

Which statement is true about applying a service-policy in the output direction?

Question 22mediummultiple choice

Consider the following configuration:

class-map match-any VOICE match ip dscp ef class-map match-any VIDEO match ip dscp af41 match ip dscp af42

What is the effect of the match-any keyword in these class-maps?

Question 23mediummultiple choice

Examine the following configuration:

policy-map SHAPE_POLICY

class class-default

shape average 10000000 service-policy INNER_POLICY

What is the purpose of the nested service-policy (service-policy INNER_POLICY) under the shape command?

Question 24mediummultiple choice

Given the following configuration:

policy-map MARKING_POLICY

class CRITICAL_DATA

set dscp af31

class BULK_DATA

set dscp af11

class class-default

set dscp default

What is the effect of the set dscp default command in the class-default?

Question 25mediummultiple choice

Consider the following configuration:

policy-map QUEUE_POLICY

class VOICE

priority level 1 police cir 1000000

class VIDEO

priority level 2 police cir 2000000

class class-default

fair-queue

What is the effect of using priority level 1 and priority level 2?

Question 26easymultiple choice

What is the default CoS-to-queue mapping on a Cisco switch that supports QoS?

Question 27easymultiple choice

Which QoS mechanism is used to prevent congestion by dropping packets before a queue becomes full?

Question 28easymultiple choice

What is the purpose of the 'police' command in a QoS policy-map?

Question 29mediumdrag order

Drag and drop the steps of the DiffServ traffic classification and marking pipeline into the correct order, from first to last.

Question 30mediumdrag order

Drag and drop the steps of the QoS trust boundary configuration process into the correct order, from first to last.

Question 31mediumdrag order

Full Practice Test →All Objectives

Drag and drop the steps of the QoS shaping and policing configuration sequence into the correct order, from first to last.

More QoS Architecture questions available in the full practice test.

Continue Practising →

Objective 104.0

QoS Architecture

350-401 Practice Questions

350-401 QoS Architecture — Practice Questions

30 questions from this objective

Question 2mediummultiple choice

A network engineer is configuring QoS on a Cisco Catalyst 9300 switch to prioritize voice traffic. The switch has multiple access ports connected to IP phones and PCs. The engineer applies a policy-map that matches DSCP EF and sets the CoS to 5. However, after testing, the voice packets are not being marked correctly. What is the most likely cause?

Question 3hardmultiple choice

An enterprise is deploying a new VoIP system and wants to ensure voice traffic receives priority over data traffic on a WAN link. The engineer configures a class-map to match RTP traffic using the 'match protocol rtp' command. However, the class-map does not match any packets. What is the most likely reason?

Question 4easymultiple choice

A network engineer is designing a QoS policy for a Cisco router that connects to an MPLS VPN. The service provider expects all traffic to be marked with IP Precedence values. The engineer wants to ensure that voice traffic (DSCP EF) is mapped to IP Precedence 5. What configuration is required on the router to perform this mapping?

Question 5mediummultiple choice

A company is implementing QoS on its campus network. The network engineer configures a policy-map that sets the CoS value for voice traffic to 5 on a switch interface. However, when the traffic reaches the router, the CoS marking is lost. What is the most likely reason?

Question 6hardmultiple choice

A network engineer is troubleshooting voice quality issues on a WAN link. The engineer notices that voice packets are being dropped during congestion. The QoS policy uses LLQ for voice traffic, but the priority queue is not providing the expected bandwidth. What is the most likely cause?

Question 7easymultiple choice

An enterprise is deploying QoS across a network that includes both Cisco and non-Cisco devices. The engineer wants to use a marking scheme that is end-to-end and not stripped at Layer 3 boundaries. Which marking field should the engineer use?

Question 8mediummultiple choice

A network engineer is configuring QoS on a Cisco router to prioritize business-critical applications. The engineer creates a class-map that matches traffic based on the destination IP address and port. However, the class-map does not match the expected traffic. What is the most likely reason?

Question 9hardmultiple choice

A network engineer is configuring QoS on a Cisco switch to ensure that video traffic (DSCP AF41) is not dropped during congestion. The engineer creates a policy-map that sets the queue-limit for the AF41 class. However, the switch is still dropping video packets. What is the most likely cause?

Question 10hardmultiple choice

A network engineer is implementing QoS on a Cisco router that connects to a service provider. The provider uses MPLS and expects the MPLS EXP bits to be set for voice traffic. The engineer configures a policy-map that sets the MPLS EXP to 5. However, the provider reports that the EXP bits are not being set. What is the most likely reason?

Question 11mediummultiple choice

An architect is designing a QoS policy for a campus LAN that must support real-time voice and video traffic alongside mission-critical data. The design must use the DiffServ model with consistent per-hop behavior across all switches. Which approach should the architect choose to ensure that voice traffic receives priority queuing while video traffic is guaranteed bandwidth without starving other classes?

Question 12mediummultiple choice

A network team is designing QoS for a Cisco SD-WAN fabric connecting multiple branch offices to a central data center. The design must ensure that VoIP traffic from branch sites receives priority treatment across the WAN overlay, regardless of the underlying transport (MPLS, Internet, LTE). Which architectural component should the team configure to enforce consistent QoS policies across all WAN edges?

Question 13mediummultiple choice

Study the full virtualization explanation →

An enterprise is deploying a leaf-spine architecture in its data center to support high-bandwidth east-west traffic. The design must include QoS to prioritize storage replication traffic (iSCSI) over backup traffic, while ensuring low latency for real-time applications. Where should the architect apply QoS classification and queuing policies in this topology?

Question 14mediummultiple choice

A company is virtualizing its network functions using NFV on a KVM-based hypervisor. The design must ensure that the virtual router (CSR1000v) can handle high-throughput traffic with minimal latency. Which architectural consideration is most critical for achieving this goal?

Question 15hardmultiple choice

Read the full wireless explanation →

An architect is designing a QoS policy for a Cisco SD-Access fabric. The policy must prioritize voice traffic from wireless clients connected to fabric-enabled access points over other traffic types. The design should use the fabric's built-in capabilities to simplify deployment. Which approach should the architect take?

Question 16hardmultiple choice

A network team is designing QoS for a multi-tenant data center using leaf-spine architecture. Each tenant requires guaranteed bandwidth for their mission-critical applications, while best-effort traffic must not interfere. The design must use hierarchical queuing to enforce per-tenant fairness. Which queuing mechanism should the architect implement on the leaf switches?

Question 17mediummultiple choice

An enterprise is designing a QoS architecture for its WAN edge routers connecting to multiple service providers. The design must support traffic shaping to avoid packet drops due to provider policers, while also prioritizing real-time traffic. Which approach should the architect use to shape traffic to the contracted CIR while still allowing bursts?

Question 18mediummultiple choice

A network architect is designing QoS for a Cisco SD-WAN deployment that uses a mix of MPLS and broadband Internet transports. The design must ensure that interactive video traffic is not delayed by large file transfers, even when the Internet link experiences congestion. Which SD-WAN policy type should the architect use to enforce this behavior?

Question 19mediummultiple choice

A company is deploying a new campus network with a hierarchical design (core, distribution, access). The QoS design must ensure that voice traffic is prioritized end-to-end, and that marking is trusted only on access ports connected to IP phones. Which architectural approach should the architect take for classification and marking?

Question 20mediummultiple choice

Consider the following configuration snippet:

policy-map QOS_POLICY

class VOICE

priority percent 30

class VIDEO

bandwidth percent 20 queue-limit 50 packets

class class-default

fair-queue queue-limit 100 packets

What is the effect of this configuration?

Question 21mediummultiple choice

Given the following configuration:

interface GigabitEthernet0/1

service-policy output QOS_POLICY

Which statement is true about applying a service-policy in the output direction?

Question 22mediummultiple choice

Consider the following configuration:

class-map match-any VOICE match ip dscp ef class-map match-any VIDEO match ip dscp af41 match ip dscp af42

What is the effect of the match-any keyword in these class-maps?

Question 23mediummultiple choice

Examine the following configuration:

policy-map SHAPE_POLICY

class class-default

shape average 10000000 service-policy INNER_POLICY

What is the purpose of the nested service-policy (service-policy INNER_POLICY) under the shape command?

Question 24mediummultiple choice

Given the following configuration:

policy-map MARKING_POLICY

class CRITICAL_DATA

set dscp af31

class BULK_DATA

set dscp af11

class class-default

set dscp default

What is the effect of the set dscp default command in the class-default?

Question 25mediummultiple choice

Consider the following configuration:

policy-map QUEUE_POLICY

class VOICE

priority level 1 police cir 1000000

class VIDEO

priority level 2 police cir 2000000

class class-default

fair-queue

What is the effect of using priority level 1 and priority level 2?

Question 26easymultiple choice

What is the default CoS-to-queue mapping on a Cisco switch that supports QoS?

Question 27easymultiple choice

Which QoS mechanism is used to prevent congestion by dropping packets before a queue becomes full?

Question 28easymultiple choice

What is the purpose of the 'police' command in a QoS policy-map?

Question 29mediumdrag order

Drag and drop the steps of the DiffServ traffic classification and marking pipeline into the correct order, from first to last.

Question 30mediumdrag order

Drag and drop the steps of the QoS trust boundary configuration process into the correct order, from first to last.

Question 31mediumdrag order