AZ-204 Develop for Azure storage — 30 Questions

Question 1

A company stores archival data in Azure Blob Storage. The data is accessed only a few times per year, and retrieval can take up to 15 hours. Which blob access tier minimizes storage costs while meeting these requirements?

Accepted Answer

Archive tier. The Archive tier is the correct choice because it is designed for data that is rarely accessed (a few times per year) and has a retrieval latency of up to 15 hours, which matches the requirement. It offers the lowest storage cost among Azure Blob Storage tiers, making it optimal for long-term archival data where infrequent access and delayed retrieval are acceptable.

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Hot tier

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Cool tier

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Premium tier

Question 2

You are building a serverless application that needs to react to insertions and updates in an Azure Cosmos DB container. You want to process these changes using an Azure Function. Which trigger should you configure for the function?

Accepted Answer

Cosmos DB trigger. A Cosmos DB trigger is the correct choice because it is specifically designed to react to changes in a Cosmos DB container by leveraging the change feed. The Azure Function runtime polls the change feed for inserts and updates, invoking the function with batches of documents as they occur. This provides a native, serverless integration without needing additional services.

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Blob trigger

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Event Grid trigger

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Service Bus trigger

Question 3

You are developing an application that writes logs to Azure Blob Storage. Each log entry is small (less than 1 KB) and you need to store millions of entries per day. You want to minimize storage costs and maximize write throughput. Which blob type should you use?

Accepted Answer

Append blobs.. Append blobs are optimized for append operations, making them ideal for logging scenarios where each log entry is appended to the blob. They provide high throughput for write-heavy, sequential append workloads and are cost-effective because they use the same block blob pricing but avoid the overhead of managing individual blocks for each small entry.

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Block blobs with a high block size.

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Page blobs.

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Block blobs with a low block size.

Question 4

You need to upload large files (up to 100 GB) to Azure Blob Storage from a web application. The upload must be resilient to network failures and support pausing/resuming. Which approach should you use?

Accepted Answer

Use block blob with multiple blocks and parallel upload.. Option B is correct because block blobs support uploading large files (up to ~4.75 TB) by splitting the file into multiple blocks, uploading them in parallel for speed, and committing the block list atomically. This approach provides resilience to network failures (individual blocks can be retried) and supports pausing/resuming by tracking which blocks have been uploaded.

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Upload the blob as a single PUT operation.

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Use append blob.

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Use AzCopy from the server.

Question 5

You need to store millions of small log entries (each <1 KB) per day from an IoT device. The logs are rarely read. Which storage solution is most cost-effective?

Accepted Answer

Azure Blob Storage Block Blob. Azure Blob Storage Block Blob is the most cost-effective solution for storing millions of small log entries (<1 KB) that are rarely read because it offers extremely low storage costs per GB, supports high-throughput ingestion, and is optimized for large-scale, append-oriented workloads. Block blobs can be stored in the 'Cool' or 'Archive' access tier to further reduce costs, and they can be efficiently batched into larger blocks (up to 100 MB per block) to minimize transaction costs.

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Azure SQL Database

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Azure Table Storage

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Azure Files

Question 6

You are developing an application that writes log entries to Azure Blob Storage. Each log entry is approximately 500 bytes, and you expect to generate millions of entries per day. The logs are rarely read, and when they are read, you need to retrieve ranges of logs sequentially. Which blob type should you use to minimize storage costs and maximize write throughput?

Accepted Answer

Append blobs. Append blobs are optimized for append operations, making them ideal for write-heavy, sequential logging scenarios. Each append operation adds data to the end of the blob, achieving high write throughput without the overhead of managing block lists. Since logs are rarely read and accessed sequentially, append blobs minimize storage costs compared to block blobs (which require block management overhead) and page blobs (which are designed for random access and are more expensive).

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Block blobs

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Page blobs

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Azure Files shares

Question 7

An application stores large media files (up to 5 GB) that are frequently appended to but rarely read sequentially. Which Azure Blob Storage type should be used to optimize writes and cost?

Accepted Answer

Append blob. Append blobs are optimized for append operations, making them ideal for scenarios like logging or storing media files that are frequently appended to. They support high-throughput writes without the overhead of managing block lists, and they are cost-effective for sequential append workloads compared to block blobs, which require explicit block management and are better suited for random read/write patterns.

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Block blob

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Page blob

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Archive blob

Question 8

You are developing a .NET Core application that stores session state data. The data is infrequently updated but must be read quickly for every user request. You need a serverless, globally distributed storage solution with low latency reads. Which Azure storage solution should you use?

Accepted Answer

Azure Cosmos DB with SQL API. Azure Cosmos DB with SQL API is the correct choice because it provides a globally distributed, serverless database service with single-digit millisecond read latency at any scale, making it ideal for infrequently updated session state that must be read quickly for every user request. Its multi-region replication ensures low-latency reads from any location, and the SQL API offers a familiar query interface for .NET Core applications.

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Azure Table Storage

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Azure Redis Cache

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Azure Blob Storage

Question 9

You need to store large binary files (up to 2 GB) that are frequently overwritten in place (entire file replaced). You want to minimize storage cost and write latency. Which Azure Blob Storage type should you use?

Accepted Answer

Block Blob. Block blobs are optimized for storing large binary files (up to ~4.75 TB) and support high-throughput uploads via PutBlock and PutBlockList operations. They allow overwriting an entire blob by uploading a new set of blocks, which minimizes write latency compared to page blobs that require sector-aligned writes. Block blobs also offer lower storage cost than page blobs, making them the best choice for frequently overwritten large files.

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Page Blob

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Append Blob

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Archive Blob

Question 10

An application writes millions of small log entries (500 bytes each) daily. The logs are rarely read, and when read, they are accessed sequentially. You need to minimize storage costs and maximize write throughput. Which Azure Blob Storage type should you use?

Accepted Answer

Append Blob. Append Blob is optimized for append operations, making it ideal for logging scenarios where new data is continuously added to the end of the blob. It provides high write throughput for small, sequential writes (like 500-byte log entries) and lower storage costs compared to Block Blob for this pattern, as it avoids the overhead of managing multiple blocks per append. Additionally, Append Blob supports sequential read access efficiently, matching the rare, sequential read requirement.

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Block Blob

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Page Blob

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Archive Blob

Question 11

You are building an IoT solution that generates millions of small log entries (each less than 1 KB) per day. The logs are rarely read, and when they are read, they are always accessed in chronological order. You need to minimize storage costs and maximize write throughput. Which Azure Blob Storage type should you use?

Accepted Answer

Append Blob. Append Blob is optimized for append operations, making it ideal for scenarios like logging where data is continuously added and rarely modified. It supports high-throughput writes because each append operation is atomic and does not require reading or updating existing blocks, which minimizes overhead. Since the logs are accessed in chronological order, Append Blob's sequential block structure allows efficient streaming reads without random access overhead.

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Block Blob

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Page Blob

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Archive Blob

Question 12

You need to store a large (terabytes) append-only dataset for compliance purposes. The data must be immutable to prevent tampering after writes. You also want to minimize storage cost and achieve high write throughput. Which Azure Storage solution should you use?

Accepted Answer

Azure Blob Storage with Append Blobs and an immutable blob policy. Azure Blob Storage with Append Blobs and an immutable blob policy is correct because Append Blobs are optimized for append-only operations (e.g., logging, audit trails) and support high write throughput. Immutable blob policies (WORM – Write Once, Read Many) enforce data immutability at the blob level, preventing modification or deletion during the retention period, which meets compliance requirements. This combination minimizes storage cost by using the cool or archive tier for Append Blobs, while still achieving the required write performance.

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Azure Data Lake Storage Gen2 with Append Blobs and immutability

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Azure Files with immutable shares

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Azure NetApp Files with immutability

Question 13

You are building a compliance solution that stores terabytes of data in Azure Blob Storage. Data is appended frequently and never modified. Regulatory requirements mandate that no data can be overwritten or deleted for 7 years. Which storage configuration should you enable?

Accepted Answer

Enable immutability policy (time-based retention). A is correct because a time-based retention policy under Azure Blob Storage immutability policy ensures that blobs cannot be overwritten or deleted for a specified duration (here, 7 years). This meets the regulatory requirement of write-once-read-many (WORM) compliance, and the policy is enforced at the storage container level, preventing any modifications or deletions even by the storage account owner.

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Enable blob soft delete

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Enable blob versioning

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Enable change feed

Question 14

You are building a data pipeline that writes billions of small log records (each ~200 bytes) to Azure Blob Storage. The logs are always written in chronological order and are read sequentially in order. You must minimize storage cost and achieve maximum write throughput. Which blob type should you use?

Accepted Answer

Append blobs in the Hot tier. Append blobs are optimized for append operations, making them ideal for writing billions of small log records in chronological order. They support high-throughput sequential writes without the overhead of managing block IDs, and the Hot tier provides low-latency access for immediate reading, minimizing storage cost while maximizing write throughput.

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Block blobs in the Cool tier

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Page blobs in the Premium tier

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Block blobs in the Archive tier

Question 15

You have an Azure Storage account that contains a blob container with thousands of small files. You need to generate a URL that allows users to download a single file for a limited time without changing the storage account's firewall rules or requiring authentication. Which approach should you use?

Accepted Answer

Create a Shared Access Signature (SAS) for the specific blob with a time limit. A Shared Access Signature (SAS) for a specific blob provides delegated, time-limited access to that blob without requiring the storage account key or changing firewall rules. By generating a SAS token with a defined expiration time and attaching it to the blob URL, users can download the file directly via HTTPS while the storage account remains secured behind its firewall and authentication requirements.

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Provide the storage account key to the user so they can authenticate

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Assign the user an RBAC role (e.g., Storage Blob Data Reader) and have them authenticate via Microsoft Entra ID

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Set the blob container's public access level to Blob (anonymous read access for blobs)

Question 16

You design an application that writes millions of small sensor readings (each ~100 bytes) to Azure Blob Storage. The data is appended to files every minute and after 7 days it is archived for compliance. You need to minimize write costs and storage costs. Which blob type and tier strategy should you use?

Accepted Answer

Append blobs with Hot tier and a lifecycle rule to move to Archive after 7 days.. Append blobs are optimized for append operations, making them ideal for continuously adding small sensor readings without rewriting existing data, which minimizes write costs. Moving the blobs to the Archive tier after 7 days via a lifecycle rule reduces storage costs for compliance data, as Archive is the lowest-cost tier for infrequently accessed data.

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Block blobs with Hot tier and a lifecycle rule to move to Cool after 7 days.

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Page blobs with Premium tier.

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Append blobs with Cool tier and no lifecycle rule.

Question 17

You need to store terabytes of archival data that must be retained for 10 years. The data is accessed once or twice per year. You need to minimize storage costs. Which Azure Storage tier should you use?

Accepted Answer

Archive. The Archive tier is designed for data that is rarely accessed (a few times per year or less) and has a flexible retrieval latency of several hours, making it ideal for long-term retention of terabytes of archival data for 10 years at the lowest storage cost. It offers the lowest per-GB storage price among Azure Blob Storage tiers, directly meeting the requirement to minimize costs for infrequently accessed data.

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Cool

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Hot

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Premium

Question 18

You are designing a solution that writes millions of small log records (each 200 bytes) to Azure Blob Storage. The logs are written every second, always appended to a single file. The file must be read periodically by a batch process that reads the entire file. You need to maximize write throughput and minimize storage costs. Which blob type and access strategy should you choose?

Accepted Answer

Use Append blobs and write each log entry as an append block. Append blobs are optimized for append operations, making them ideal for writing millions of small log records sequentially to a single file. Each log entry is written as an append block, which provides high throughput for append-heavy workloads. Append blobs also minimize storage costs because they store data in a single blob without the overhead of managing multiple blobs or pages.

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Use Block blobs and append the data to a single blob

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Use Page blobs and write each log entry to a page

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Use Block blobs and create a new blob for each log entry

Question 19

You need to store large files that are written once and then frequently read for the first 30 days. After 30 days, the files are rarely accessed (once or twice per year) but must remain available for 5 years. You want to minimize storage costs. Which storage tier and lifecycle management rule should you apply?

Accepted Answer

Hot tier with a lifecycle rule to move to Cool after 30 days. Option A is correct because the Hot tier is optimized for frequent reads, and the lifecycle rule moves data to the Cool tier after 30 days when access drops, balancing performance and cost. After 30 days, the files are rarely accessed, so moving them to Cool (not Archive) keeps them available for occasional reads without the high retrieval costs and latency of Archive. This minimizes storage costs while meeting the 5-year retention requirement.

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Cool tier with a lifecycle rule to move to Archive after 30 days

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Hot tier with a lifecycle rule to move to Archive after 30 days

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Archive tier with a lifecycle rule to move to Cool after 30 days

Question 20

You need to store billions of small log entries (each ~200 bytes) written in chronological order from multiple producers. The logs are read sequentially in bulk once per day. You need to maximize write throughput and minimize storage costs. Which Azure Storage solution should you choose?

Accepted Answer

Append Blob in Blob Storage. Append Blob in Blob Storage is optimized for append operations, making it ideal for writing small log entries in chronological order from multiple producers. It provides high write throughput because each append operation is atomic and can be performed concurrently, and it minimizes storage costs by storing data in a cost-effective blob tier without the overhead of indexing or metadata management required by other solutions.

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Block Blob in Blob Storage with high block count

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Azure Data Lake Storage Gen2 with hierarchical namespace

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Azure Files with SMB protocol