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Develop Azure compute solutions →mediumMultiple ChoiceObjective-mapped

Quick Answer

The most likely cause is that the storage account connection string is not set in the function app settings. Azure Functions rely on the `AzureWebJobsStorage` app setting (or a custom connection property in the binding) to authenticate with Blob Storage; without it, the output binding silently fails to write the blob even though the HTTP trigger executes successfully. This scenario tests your understanding of how Azure Functions manage external dependencies via application settings, a key concept for the AZ-204 exam. A common trap is assuming the function runs correctly just because the HTTP trigger returns a 200 status, but the output binding requires explicit storage configuration to function. Remember: the trigger can fire, but the binding cannot bind without a connection string. Memory tip: “No string, no blob—the trigger runs, but the blob stays home.”

AZ-204 Develop Azure compute solutions Practice Question

This AZ-204 practice question tests your understanding of develop azure compute solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.

Exhibit

public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequest req,
    [Blob("samples-workitems/{rand-guid}", FileAccess.Write)] Stream blobStream,
    ILogger log)
{
    string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
    byte[] bytes = Encoding.UTF8.GetBytes(requestBody);
    await blobStream.WriteAsync(bytes, 0, bytes.Length);
    return new OkResult();
}

Refer to the exhibit. You have an HTTP-triggered Azure Function that writes the request body to a blob in the 'samples-workitems' container. The function runs successfully but does not create a blob. What is the most likely cause?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "most likely"

    Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1mediummultiple choice
Full question →

Exhibit

public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequest req,
    [Blob("samples-workitems/{rand-guid}", FileAccess.Write)] Stream blobStream,
    ILogger log)
{
    string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
    byte[] bytes = Encoding.UTF8.GetBytes(requestBody);
    await blobStream.WriteAsync(bytes, 0, bytes.Length);
    return new OkResult();
}

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

✓

The storage account connection string is not set in the function app settings

The most likely cause is that the storage account connection string is not set in the function app settings. Azure Functions require the connection string for the storage account to be configured via the `AzureWebJobsStorage` app setting (or a custom connection setting referenced in the binding). Without it, the runtime cannot authenticate or communicate with Blob Storage, so the output binding silently fails to write the blob, even though the function executes successfully.

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.

  • ✗

    The container name 'samples-workitems' is invalid

    Why it's wrong here

    Wrong: The name is valid (lowercase, no special chars except dash).

  • ✗

    The blob name pattern {rand-guid} is not supported

    Why it's wrong here

    Wrong: {rand-guid} is a supported binding expression.

  • ✓

    The storage account connection string is not set in the function app settings

    Why this is correct

    Correct: Without the connection string, the binding cannot connect to storage.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • ✗

    The blob output binding syntax is incorrect

    Why it's wrong here

    Wrong: The syntax is correct for a blob output binding.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume the function code itself must be wrong (e.g., invalid container name or binding syntax) when the issue is a missing configuration setting that the Azure Functions runtime requires to connect to storage.

Trap categories for this question

  • Command / output trap

    Wrong: The syntax is correct for a blob output binding.

Detailed technical explanation

How to think about this question

The `AzureWebJobsStorage` app setting holds the connection string for the default storage account used by the Functions runtime for internal operations (like managing triggers and bindings). When a blob output binding does not specify a custom `connection` property, it defaults to `AzureWebJobsStorage`. If this setting is missing or invalid, the binding cannot create a connection to Blob Storage, and the write operation fails silently—no exception is thrown in the function code because the binding is evaluated at runtime by the WebJobs SDK. In real-world scenarios, this often happens when deploying to a new environment without copying the connection string from the development settings.

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.

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 AZ-204 question test?

Develop Azure compute solutions — This question tests Develop Azure compute solutions — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The storage account connection string is not set in the function app settings — The most likely cause is that the storage account connection string is not set in the function app settings. Azure Functions require the connection string for the storage account to be configured via the `AzureWebJobsStorage` app setting (or a custom connection setting referenced in the binding). Without it, the runtime cannot authenticate or communicate with Blob Storage, so the output binding silently fails to write the blob, even though the function executes successfully.

What should I do if I get this AZ-204 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 24, 2026

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