350-501 · topic practice
Practise Cisco SPCOR / CCNP Service Provider Core 350-501 Automation and Quality of Services practice questions — original exam-style scenarios with answer choices, explanations, and analysis of common mistakes.
Courseiva uses original exam-style practice questions designed for learning and revision. The goal is to understand the concepts, recognise exam patterns, and improve through explanations — not memorise copied exam dumps.
What the exam tests
Automation and Quality of Services questions test whether you can apply the concept in context, not just recognise a definition.
How the topic appears in realistic exam-style scenarios.
Which detail in the question changes the correct answer.
How to eliminate plausible but wrong options.
How to connect the question back to the wider exam objective.
Watch out for
Practice set
20 questions · select your answer, then reveal the explanation
Trap 1: DSCP 0
DSCP 0 is Best Effort (DF).
Trap 2: DSCP 40
DSCP 40 is not EF; EF is 46.
Trap 3: DSCP 34
DSCP 34 is AF41, not EF.
DSCP 0
Why wrong: DSCP 0 is Best Effort (DF).
DSCP 46
EF is DSCP 46 as per RFC 3246.
DSCP 40
Why wrong: DSCP 40 is not EF; EF is 46.
DSCP 34
Why wrong: DSCP 34 is AF41, not EF.
Trap 1: Define parent policy-map with shape, then child policy-map with…
Child should be applied via parent's service-policy, not directly.
Trap 2: Use policing in the parent policy to enforce 10 Mbps and child for…
Parent should shape, not police, for traffic smoothing under contract.
Trap 3: Define one policy-map with both shape and LLQ in the same class.
Hierarchical QoS requires separate parent and child policies.
Define parent policy-map with shape, then child policy-map with LLQ, apply child directly to interface.
Why wrong: Child should be applied via parent's service-policy, not directly.
Use policing in the parent policy to enforce 10 Mbps and child for LLQ.
Why wrong: Parent should shape, not police, for traffic smoothing under contract.
Define one policy-map with both shape and LLQ in the same class.
Why wrong: Hierarchical QoS requires separate parent and child policies.
Define child class-map and policy-map with LLQ, then parent policy-map with shape and service-policy child, applied to interface.
This correctly implements H-QoS: child policy first, then parent with shape and child policy reference.
Trap 1: EXP bits are always copied from the IP DSCP at the ingress PE.
Only in Uniform model; in Pipe models, EXP is set separately.
Trap 2: In Pipe model, the egress PE uses EXP bits for queuing.
In Pipe, egress uses EXP; in Short Pipe, egress uses IP DSCP.
Trap 3: The MPLS EXP field is 6 bits, same as DSCP.
EXP is 3 bits (8 values).
EXP bits are always copied from the IP DSCP at the ingress PE.
Why wrong: Only in Uniform model; in Pipe models, EXP is set separately.
In Pipe model, the egress PE uses EXP bits for queuing.
Why wrong: In Pipe, egress uses EXP; in Short Pipe, egress uses IP DSCP.
The MPLS EXP field is 6 bits, same as DSCP.
Why wrong: EXP is 3 bits (8 values).
In Short Pipe model, the egress PE uses the original IP DSCP for queuing decisions, not the EXP.
Short Pipe uses IP DSCP at egress, not EXP.
Trap 1: YANG
YANG is a data modeling language, not a driver.
Trap 2: RESTCONF
RESTCONF is a protocol, not a device abstraction layer.
Trap 3: CDB
CDB is the configuration database, not the device driver.
YANG
Why wrong: YANG is a data modeling language, not a driver.
NED
NED abstracts device specifics.
RESTCONF
Why wrong: RESTCONF is a protocol, not a device abstraction layer.
CDB
Why wrong: CDB is the configuration database, not the device driver.
Trap 1: <edit-config> on candidate, then <copy-config> to running
Cisco uses <commit> instead of <copy-config>.
Trap 2: <edit-config> on running, no lock needed
Editing running directly is not supported on IOS XR; candidate model is used.
Trap 3: <lock>, <edit-config>, <commit>, <unlock>
IOS XR uses candidate config; <commit> is needed after <edit-config>.
<edit-config> on candidate, then <copy-config> to running
Why wrong: Cisco uses <commit> instead of <copy-config>.
<lock>, <edit-config> on candidate, <commit>, <unlock>
This is the standard candidate config workflow.
<edit-config> on running, no lock needed
Why wrong: Editing running directly is not supported on IOS XR; candidate model is used.
<lock>, <edit-config>, <commit>, <unlock>
Why wrong: IOS XR uses candidate config; <commit> is needed after <edit-config>.
Trap 1: RESTCONF
RESTCONF is not used for PCE-PCC communication.
Trap 2: NETCONF
NETCONF is for configuration management, not path computation.
Trap 3: BGP-LS
BGP-LS carries topology information to PCE, not for LSP setup.
RESTCONF
Why wrong: RESTCONF is not used for PCE-PCC communication.
NETCONF
Why wrong: NETCONF is for configuration management, not path computation.
BGP-LS
Why wrong: BGP-LS carries topology information to PCE, not for LSP setup.
PCEP
PCEP handles path computation and delegation.
Trap 1: Policing buffers excess traffic, while shaping drops it.
Opposite: policing drops, shaping buffers.
Trap 2: Policing is only applied inbound, shaping only outbound.
Both can be applied inbound/outbound, but shaping is typically outbound.
Trap 3: Both policing and shaping buffer excess traffic.
Only shaping buffers.
Shaping buffers excess traffic, while policing drops or re-marks it.
Correct description.
Policing buffers excess traffic, while shaping drops it.
Why wrong: Opposite: policing drops, shaping buffers.
Policing is only applied inbound, shaping only outbound.
Why wrong: Both can be applied inbound/outbound, but shaping is typically outbound.
Both policing and shaping buffer excess traffic.
Why wrong: Only shaping buffers.
Trap 1: Use CBWFQ without LLQ.
LLQ is needed for voice, but policing is still required.
Trap 2: Disable queueing on other classes.
That would not help.
Trap 3: Set the priority queue bandwidth to 100%.
This would starve other queues.
Configure a policer on the LLQ class to limit its rate.
Policing within LLQ is recommended to protect other classes.
Use CBWFQ without LLQ.
Why wrong: LLQ is needed for voice, but policing is still required.
Disable queueing on other classes.
Why wrong: That would not help.
Set the priority queue bandwidth to 100%.
Why wrong: This would starve other queues.
Trap 1: They conditionally make a leaf mandatory.
'mandatory' statement or 'when' does that.
Trap 2: They are used to refine types.
Refinements are done with 'type' statement.
Trap 3: They are used to define default values.
Default values are defined with 'default' statement.
They conditionally make a leaf mandatory.
Why wrong: 'mandatory' statement or 'when' does that.
They are used to refine types.
Why wrong: Refinements are done with 'type' statement.
They are used to define default values.
Why wrong: Default values are defined with 'default' statement.
They enforce a constraint that must be true for the data to be valid.
'must' specifies an XPath expression that must evaluate to true.
Trap 1: must 'current() = /vpn-list/vpn-id';
This must expression would be complex and not standard; leafref is designed for this.
Trap 2: mandatory true;
Mandatory ensures presence, not validity against a list.
Trap 3: type string { pattern '[0-9]+'; }
Pattern only validates format, not existence.
must 'current() = /vpn-list/vpn-id';
Why wrong: This must expression would be complex and not standard; leafref is designed for this.
type leafref { path '/vpn-list/vpn-id'; }
leafref with path ensures the value exists in the referenced leaf.
mandatory true;
Why wrong: Mandatory ensures presence, not validity against a list.
type string { pattern '[0-9]+'; }
Why wrong: Pattern only validates format, not existence.
Trap 1: Service-policy
Service-policy applies the policy to an interface.
Trap 2: Policy-map
Policy-map defines actions, not classification.
Trap 3: Access-list
Access-list can be used within class-map, but class-map is the MQC component.
Class-map
Class-map uses match statements to identify traffic.
Service-policy
Why wrong: Service-policy applies the policy to an interface.
Policy-map
Why wrong: Policy-map defines actions, not classification.
Access-list
Why wrong: Access-list can be used within class-map, but class-map is the MQC component.
Trap 1: fair-queue
Fair-queue is default for class-default.
Trap 2: priority percent 30
Priority creates LLQ, not CBWFQ.
Trap 3: bandwidth 30
Without 'percent', it's in kbps.
fair-queue
Why wrong: Fair-queue is default for class-default.
priority percent 30
Why wrong: Priority creates LLQ, not CBWFQ.
bandwidth percent 30
Correct way to specify percentage.
bandwidth 30
Why wrong: Without 'percent', it's in kbps.
Trap 1: CS0
CS0 is best effort.
Trap 2: AF11
AF1 is low priority, typically scavenger.
Trap 3: AF22
AF2 is medium priority, but typically not 'mission-critical'.
CS0
Why wrong: CS0 is best effort.
AF11
Why wrong: AF1 is low priority, typically scavenger.
AF41
AF4 class is high priority.
AF22
Why wrong: AF2 is medium priority, but typically not 'mission-critical'.
AF31
AF3 class is also high priority.
Trap 1: Java API
Java API is for development, not a core component.
Trap 2: SNMP
NSO primarily uses NETCONF/RESTCONF/CLI, not SNMP.
Java API
Why wrong: Java API is for development, not a core component.
YANG service model
Service models in YANG define the service logic.
SNMP
Why wrong: NSO primarily uses NETCONF/RESTCONF/CLI, not SNMP.
CDB
Configuration database stores device and service configs.
NED
Network Element Driver abstracts device specifics.
Trap 1: POST
POST creates, but the question asks for retrieving data.
Trap 2: PATCH
PATCH modifies.
Trap 3: PUT
PUT creates/replaces.
GET
GET retrieves resource representation.
POST
Why wrong: POST creates, but the question asks for retrieving data.
PATCH
Why wrong: PATCH modifies.
PUT
Why wrong: PUT creates/replaces.
DELETE
Why wrong: DELETE removes.
Trap 1: DSCP 10
DSCP 10 is AF11.
Trap 2: DSCP 0
DSCP 0 is Best Effort (DF).
Trap 3: DSCP 34
DSCP 34 is not EF; it corresponds to AF41.
DSCP 46
EF is DSCP 46, used for voice.
DSCP 10
Why wrong: DSCP 10 is AF11.
DSCP 0
Why wrong: DSCP 0 is Best Effort (DF).
DSCP 34
Why wrong: DSCP 34 is not EF; it corresponds to AF41.
Trap 1: CBWFQ
CBWFQ provides bandwidth allocation, not rate enforcement.
Trap 2: Traffic shaping
Shaping buffers excess traffic; it does not drop but smooths bursts.
Trap 3: LLQ
LLQ is a queuing mechanism for priority traffic, not rate limiting.
Policing
Policing drops or re-marks packets exceeding the rate, enforcing a hard limit.
CBWFQ
Why wrong: CBWFQ provides bandwidth allocation, not rate enforcement.
Traffic shaping
Why wrong: Shaping buffers excess traffic; it does not drop but smooths bursts.
LLQ
Why wrong: LLQ is a queuing mechanism for priority traffic, not rate limiting.
Trap 1: YANG model
YANG models define data structures, not device communication.
Trap 2: CDB (Configuration Database)
CDB stores configuration and operational data, not device abstraction.
Trap 3: RESTCONF northbound API
Northbound API connects to OSS/BSS, not device abstraction.
YANG model
Why wrong: YANG models define data structures, not device communication.
CDB (Configuration Database)
Why wrong: CDB stores configuration and operational data, not device abstraction.
RESTCONF northbound API
Why wrong: Northbound API connects to OSS/BSS, not device abstraction.
NED (Network Element Driver)
NED abstracts device-specific operations to a common YANG model.
Trap 1: edit-config
edit-config modifies configuration.
Trap 2: get
get retrieves configuration and state data, not just config.
Trap 3: lock
lock locks the configuration datastore.
edit-config
Why wrong: edit-config modifies configuration.
get
Why wrong: get retrieves configuration and state data, not just config.
get-config
get-config with source running retrieves the running configuration.
lock
Why wrong: lock locks the configuration datastore.
Trap 1: Apply shaping on the interface and queuing on a subinterface…
Hierarchical QoS uses nested policy-maps, not separate interface configurations.
Trap 2: Use a child policy-map for shaping and a parent policy-map for…
Shaping is applied in the parent, queuing in the child.
Trap 3: Apply a single policy-map with both shape and queue commands under…
Hierarchical QoS requires separate parent and child policies.
Apply shaping on the interface and queuing on a subinterface separate from the policy-map.
Why wrong: Hierarchical QoS uses nested policy-maps, not separate interface configurations.
Use a child policy-map for shaping and a parent policy-map for queuing.
Why wrong: Shaping is applied in the parent, queuing in the child.
Configure a parent policy-map with shape and a child policy-map with queuing, then apply the child under the parent's class.
This is the correct hierarchical QoS design: parent shapes, child queues.
Apply a single policy-map with both shape and queue commands under the same class.
Why wrong: Hierarchical QoS requires separate parent and child policies.
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