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350-401 Practice Question: Which two statements about YANG data models and…
Which two statements about YANG data models and their role in model-driven telemetry are true? (Choose two.)
⚠ Common exam trap
A common mix-up: candidates confuse YANG with a transport protocol or thinking OpenConfig models are vendor-specific; candidates might also think only IETF models are used for telemetry.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
YANG is a data modeling language used to define the structure of configuration and operational state data.
Option A is correct because YANG (RFC 6020/7950) is a data modeling language that defines the hierarchical structure, syntax, and semantics of configuration data and operational state data on network devices, which is the foundation for model-driven telemetry. Option C is correct because native YANG models are authored by the device vendor (e.g., Cisco IOS XE native models) and can expose platform-specific features and proprietary data nodes not covered by standard models. Option B is incorrect because OpenConfig YANG models are vendor-neutral, community-developed models intended to work across multiple vendors, not vendor-specific or Cisco-only. Option D is incorrect because model-driven telemetry subscriptions can use native, OpenConfig, and IETF YANG models, not IETF models exclusively. Option E is incorrect because YANG is a modeling language, not a transport protocol; telemetry streaming is carried by protocols such as gRPC, NETCONF, or RESTCONF.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
YANG is a data modeling language used to define the structure of configuration and operational state data.
Why this is correct
YANG defines hierarchical schemas for configuration and operational state, using containers, lists and leaves to model device data. This structure underpins model-driven telemetry, where subscribed paths stream state changes, satisfying the stem's requirement that YANG models both configuration and operational data.
- ✗
OpenConfig YANG models are vendor-specific and only supported on Cisco devices.
Why it's wrong here
OpenConfig models are vendor-neutral, developed collaboratively across vendors, not Cisco-specific. They tempt because Cisco supports and contributes to OpenConfig, and vendor-native models do exist, but OpenConfig's defining trait is cross-vendor interoperability rather than single-vendor lock-in.
- ✓
Native YANG models are developed by the device vendor and may expose platform-specific features.
Why this is correct
Native YANG models are vendor-authored, so they can expose platform-specific features and CLI-equivalent knobs that standard models omit. This satisfies the stem's requirement for a true statement about YANG's role in model-driven telemetry, where vendor-native paths are commonly subscribed to for granular, device-unique operational data.
- ✗
IETF YANG models are the only models that can be used for model-driven telemetry subscriptions.
Why it's wrong here
Telemetry subscriptions can use IETF, OpenConfig or vendor-native YANG models; IETF models hold no exclusivity. The appeal is that IETF models are standards-based and widely implemented, yet model choice depends on device support and required data, not on a single mandated family.
- ✗
YANG is a transport protocol used to stream telemetry data from network devices to collectors.
Why it's wrong here
YANG is a data modelling language defining configuration and state schemas; streaming uses gRPC, NETCONF or UDP-based transports. The confusion arises because YANG models drive telemetry payloads, so it appears transport-adjacent, but it never carries data itself between devices and collectors.
Go deeper
Related to this question
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Key term
NETCONF Protocol
NETCONF is a network management protocol that uses a structured data format to configure, retrieve, and modify network devices in a standard, programmatic way.
Key term
REST API for Network Devices
A REST API for network devices is a set of rules that allows software applications to communicate with routers, switches, and firewalls using standard web methods like GET, POST, PUT, and DELETE over HTTP or HTTPS.
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Same concept, more angles
1 more way this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which two statements about YANG data models in model-driven telemetry are true? (Choose two.)
medium- ✓ A.YANG models are used to define the data structures streamed in telemetry subscriptions.
- ✓ B.OpenConfig YANG models are vendor-neutral and supported across multiple network operating systems.
- C.Native YANG models are standardized by the IETF and used universally.
- D.NETCONF is a YANG data model used for telemetry configuration.
- E.RESTCONF provides a YANG-based data model for streaming telemetry.
Why A: Option A is correct because YANG (RFC 7950) defines the schema and data structures—containers, lists, leaves, and paths—that model-driven telemetry subscriptions reference when selecting which operational data to stream. Option B is correct because OpenConfig YANG models are developed collaboratively and vendor-neutral, so they can be supported across multiple network operating systems such as Cisco IOS XE, Junos, and others, enabling consistent telemetry paths. Option C is wrong because native YANG models are vendor-specific (e.g., Cisco or Juniper native models), not IETF-standardized; the IETF standardizes models like ietf-interfaces, not all native models. Option D is wrong because NETCONF (RFC 6241) is a protocol, not a YANG data model, and it is used for configuration/state retrieval rather than being a telemetry model. Option E is wrong because RESTCONF (RFC 8040) is an HTTP-based protocol for accessing YANG-modeled data, not a YANG data model itself, and streaming telemetry is typically delivered via gRPC, gNMI, or UDP-based push rather than RESTCONF.
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.