The answer is Azure Blob Storage and Azure Cosmos DB. Both services support storing JSON documents without requiring a predefined schema, but they do so in fundamentally different ways. Azure Blob Storage treats JSON files as opaque binary data within block blobs, offering no schema enforcement at the storage layer—you simply upload and retrieve the raw JSON. Azure Cosmos DB, by contrast, natively understands JSON and provides a flexible schema-agnostic document model, allowing you to insert, query, and index JSON documents without defining a schema upfront. On the AZ-305 exam, this distinction tests your understanding of storage versus database services for schema-less workloads; a common trap is assuming only Cosmos DB qualifies, but Blob Storage’s ability to store any JSON file as a blob makes it equally valid. Remember the memory tip: “Blobs are blind to schema, Cosmos embraces it without one.”
AZ-305 Design data storage solutions Practice Question
This AZ-305 practice question tests your understanding of design data storage solutions. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 TWO of the following Azure services support storing JSON documents without requiring a predefined schema? (Select two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Blob Storage
Azure Blob Storage is correct because it can store JSON documents as blobs (block blobs) without requiring a predefined schema. The service treats the JSON as opaque binary data, allowing you to upload, download, and manage JSON files with no schema enforcement, making it suitable for schema-less document storage.
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.
✗
Azure Purview
Why it's wrong here
Purview is a data governance service, not a storage service.
✓
Azure Blob Storage
Why this is correct
Blob Storage can store JSON files as blobs without schema enforcement.
Related concept
Read the scenario before looking for a memorised answer.
✓
Azure Cosmos DB
Why this is correct
Cosmos DB is a NoSQL database that stores schema-less JSON documents.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Analysis Services
Why it's wrong here
Analysis Services is for tabular data models, not document storage.
✗
Azure SQL Database
Why it's wrong here
Azure SQL Database requires a predefined schema for tables.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may mistakenly think Azure SQL Database's JSON support (e.g., OPENJSON, JSON_VALUE) means it can store JSON without a schema, but in reality, the JSON must be inserted into a predefined table column, so the table schema is still required.
Detailed technical explanation
How to think about this question
Under the hood, Azure Blob Storage stores JSON as a sequence of bytes in a block blob, with no indexing or querying capabilities unless you layer on Azure Data Lake Storage or use external tools. Azure Cosmos DB, on the other hand, natively indexes JSON documents using its schema-agnostic indexing engine, automatically indexing every property without requiring a predefined schema, and supports SQL-like queries via its core (SQL) API. A real-world scenario is storing IoT sensor data as JSON blobs in Blob Storage for archival, while using Cosmos DB for real-time querying of the same data.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-305 question in full detail.
Design data storage solutions — This question tests Design data storage solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Azure Blob Storage — Azure Blob Storage is correct because it can store JSON documents as blobs (block blobs) without requiring a predefined schema. The service treats the JSON as opaque binary data, allowing you to upload, download, and manage JSON files with no schema enforcement, making it suitable for schema-less document storage.
What should I do if I get this AZ-305 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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Question Discussion
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