- A
RADIUS server
Why wrong: RADIUS is for AAA, not NSO architecture.
- B
YANG models for service definitions
YANG models define service structures in NSO.
- C
PCEP (Path Computation Element Protocol)
Why wrong: PCEP is used for SR-TE, not part of NSO core.
- D
CDB (Configuration Database)
CDB stores the actual device configurations.
- E
NED (Network Element Driver)
NEDs abstract device-specific CLI/Netconf.
Question 452 of 1,000
350-501 Automation and Quality of Services Practice Question
This 350-501 practice question tests your understanding of automation and quality of services. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which three components are part of NSO (Network Services Orchestrator) architecture? (Choose three.)
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 for service definitions
YANG models are the foundation for service definitions in NSO because they define the data structures and constraints for network services using a standardized modeling language (RFC 6020/7950). NSO uses YANG to model both the service layer (customer-facing services) and the device layer (native device configurations), enabling service abstraction and multi-vendor orchestration.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
RADIUS server
- ✓
YANG models for service definitions
Why this is correct
YANG models define service structures in NSO.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
PCEP (Path Computation Element Protocol)
Why it's wrong here
PCEP is used for SR-TE, not part of NSO core.
- ✓
CDB (Configuration Database)
Why this is correct
CDB stores the actual device configurations.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
NED (Network Element Driver)
Why this is correct
NEDs abstract device-specific CLI/Netconf.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between protocols that NSO can orchestrate (like PCEP for path computation) versus components that are part of NSO's internal architecture (like NEDs, CDB, and YANG models), leading candidates to mistakenly select external protocols as architectural components.
Detailed technical explanation
How to think about this question
NSO's CDB (Configuration Database) is an in-memory, transactional database that stores the intended configuration state, using a two-phase commit protocol to ensure consistency across devices. NEDs (Network Element Drivers) translate YANG-modeled data into device-specific CLI or NETCONF commands, allowing NSO to manage devices from different vendors without custom scripting. A real-world scenario is a service provider using NSO to deploy a Layer 3 VPN across Cisco, Juniper, and Huawei routers, where YANG models define the service, NEDs handle per-vendor syntax, and CDB maintains the transactional state.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this 350-501 question test?
Automation and Quality of Services — This question tests Automation and Quality of Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: YANG models for service definitions — YANG models are the foundation for service definitions in NSO because they define the data structures and constraints for network services using a standardized modeling language (RFC 6020/7950). NSO uses YANG to model both the service layer (customer-facing services) and the device layer (native device configurations), enabling service abstraction and multi-vendor orchestration.
What should I do if I get this 350-501 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This 350-501 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 350-501 exam.
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