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350-401 Practice Question: Which two statements about YANG data models in…
Which two statements about YANG data models in model-driven telemetry are true? (Choose two.)
⚠ Common exam trap
350-401 often tests the confusion between protocols and data models — candidates may think NETCONF or RESTCONF are YANG models, but they are transport protocols that use YANG.
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 models are used to define the data structures streamed in telemetry subscriptions.
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.
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 models are used to define the data structures streamed in telemetry subscriptions.
Why this is correct
YANG provides the schema that describes the hierarchical data nodes a device exposes, so telemetry subscriptions reference those paths to select which counters and state values are streamed, satisfying the requirement for structured, model-driven data encoding.
- ✓
OpenConfig YANG models are vendor-neutral and supported across multiple network operating systems.
Why this is correct
OpenConfig models are defined independently of any single vendor, so the same YANG schema can drive telemetry subscriptions on devices from different manufacturers. This satisfies the interoperability requirement when streaming data across a multivendor network.
- ✗
Native YANG models are standardized by the IETF and used universally.
Why it's wrong here
Native YANG models are vendor-specific, published by each vendor for its own platform, not standardised by the IETF. IETF standardises open models such as those in RFC 8343. It is tempting because native models are YANG-based and widely deployed, but universality across vendors belongs to standard models, not native ones.
- ✗
NETCONF is a YANG data model used for telemetry configuration.
Why it's wrong here
NETCONF is a transport protocol that carries YANG-modelled data; it is not itself a YANG model. YANG defines the schema, NETCONF encodes operations over SSH. It is tempting because NETCONF and YANG are always deployed together, and NETCONF is used to configure telemetry subscriptions, but the protocol and the modelling language are distinct layers.
- ✗
RESTCONF provides a YANG-based data model for streaming telemetry.
Why it's wrong here
RESTCONF is a protocol providing HTTP-based access to YANG-modelled data; it does not itself supply a YANG data model, and it is not the streaming telemetry mechanism. It is tempting because RESTCONF and YANG are tightly coupled, and RESTCONF can configure subscriptions, but streaming delivery uses gRPC or NETCONF dial-out.
Go deeper
Related to this question
Learn chapter
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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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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.