200-901 Infrastructure and Automation Practice Question
Which data format is most commonly used in REST API requests and responses in modern network automation?
⚠ Common exam trap
Many exam-takers confuse YAML's prevalence in configuration management (e.g., Ansible) with REST API data interchange, or assume XML's historical role in SOAP extends to modern REST, leading them to overlook JSON's dominance in actual API payloads.
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
✓
JSON
JSON (JavaScript Object Notation) is the most commonly used data format in REST API requests and responses for modern network automation because it is lightweight, language-agnostic, and natively supported by most programming languages and network devices. REST APIs typically use JSON over HTTP due to its ease of parsing, compact structure, and alignment with web development practices, making it the de facto standard for exchanging structured data in automation workflows like those with Cisco NSO, Ansible, or Python scripts.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
YAML
Why it's wrong here
YAML is a human-readable configuration and data-serialisation language, but REST APIs in network automation exchange JSON by default, and most controllers and libraries parse JSON natively. YAML is the correct choice for Ansible playbooks, CI pipeline definitions and other configuration files where readability by humans matters more than machine parsing.
- ✗
XML
Why it's wrong here
XML is verbose and heavyweight compared with JSON, which has become the default payload format for REST APIs in modern network automation tooling. XML is the correct choice for SOAP-based APIs, legacy NETCONF configuration retrieval and document formats requiring strict schema validation through XSD.
- ✗
CSV
Why it's wrong here
CSV is a flat tabular format lacking the nested structures REST APIs require for objects and arrays, so it cannot represent typical JSON payloads. REST endpoints in network automation expect JSON bodies. CSV is the correct choice for exporting tabular data such as inventory spreadsheets or bulk device lists into reporting tools.
- ✓
JSON
Why this is correct
JSON dominates REST API payloads because its lightweight, human-readable key-value structure maps directly onto HTTP request bodies and parses natively in Python, satisfying the modern network automation requirement for simple serialisation between scripts and controllers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 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 200-901 exam.