CCNA AI and Network Operations Practice Question
Which data format uses key-value pairs and is commonly returned by REST APIs?
⚠ Common exam trap
Be careful not to confuse JSON with XML or YAML, which have different structures and use cases.
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 is a lightweight, human-readable data format that uses key-value pairs and is the most common format returned by REST APIs. YANG is a data modeling language used for configuration and state data, not a data format. Syslog is a logging protocol used for system messages. CDP (Cisco Discovery Protocol) is a Layer 2 discovery protocol for Cisco devices. None of these are key-value pair data formats typically returned by REST APIs.
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
Why it's wrong here
YANG is a modeling language, not the usual wire-format response body.
When this WOULD be correct
If the question asked which data modeling language is used for network device configuration and management, YANG would be the correct answer. This scenario would focus on network protocols and data structure definitions rather than API responses.
- ✓
JSON
Why this is correct
JSON commonly represents API payloads.
- ✗
Syslog
Why it's wrong here
Syslog is a logging protocol and message format.
When this WOULD be correct
If the question were to ask about a logging format used for network devices that can include key-value pairs in its extended format, Syslog could be the correct answer. For example, a question about logging protocols that support structured data might fit this scenario.
- ✗
CDP
Why it's wrong here
CDP is a Cisco discovery protocol.
When this WOULD be correct
If the exam question asked about protocols used for device discovery in a Cisco network environment, CDP would be the correct answer, as it is specifically designed for that purpose.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓JSONCorrect answer▾
Why this is correct
JSON commonly represents API payloads.
✗YANGWrong answer — click to see why▾
Why this is wrong here
YANG is a data modeling language used to define the structure of configuration and state data, not a data format for API responses. REST APIs typically return data in JSON or XML, not YANG models.
★ When this WOULD be the correct answer
If the question asked which data modeling language is used for network device configuration and management, YANG would be the correct answer. This scenario would focus on network protocols and data structure definitions rather than API responses.
Why candidates choose this
Students may confuse YANG with JSON because both are used in network automation and RESTCONF/NETCONF APIs, but YANG defines the schema while JSON is the actual wire format.
✗SyslogWrong answer — click to see why▾
Why this is wrong here
Syslog is a protocol and message format for logging system events, not a data format for API responses. It uses a specific structured format with facility, severity, and message fields, but not key-value pairs like JSON.
★ When this WOULD be the correct answer
If the question were to ask about a logging format used for network devices that can include key-value pairs in its extended format, Syslog could be the correct answer. For example, a question about logging protocols that support structured data might fit this scenario.
Why candidates choose this
Students might think syslog uses key-value pairs because some syslog messages include structured data, but the standard syslog format is not key-value based and is not used for REST API responses.
✗CDPWrong answer — click to see why▾
Why this is wrong here
CDP (Cisco Discovery Protocol) is a proprietary Layer 2 protocol used by Cisco devices to discover neighboring devices, not a data format. It does not use key-value pairs and is not returned by REST APIs.
★ When this WOULD be the correct answer
If the exam question asked about protocols used for device discovery in a Cisco network environment, CDP would be the correct answer, as it is specifically designed for that purpose.
Why candidates choose this
The acronym CDP might be confused with JSON because both are related to network data, but CDP is a discovery protocol, not a data format. Students may also confuse it with other protocols like LLDP.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Interpreting Syslog Messages, Severity Levels, and Facilities
Key term
YANG
YANG is a data modeling language used to define the structure and constraints of data exchanged between network devices and management applications.
Key term
JSON
JSON is a lightweight, text-based format for storing and exchanging data that is easy for humans to read and write and easy for machines to parse and generate.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.