Quick Answer
The answer is using a system-assigned managed identity, which is one of three valid ways to authenticate Azure Functions to Azure Service Bus. This method works because DefaultAzureCredential from the Azure Identity library can authenticate to Azure Service Bus using Azure AD tokens, and when deployed, the managed identity automatically provides a secure, credential-free identity for the function app. The credential chain attempts multiple authentication sources—environment variables, managed identity, Visual Studio, and others—to obtain a token, which is then used to authorize requests to the Service Bus namespace via Azure RBAC. On the AZ-204 exam, this tests your understanding of identity-based authentication versus connection strings or SAS keys, and a common trap is assuming only shared access policies are valid. The other two valid methods are using a connection string with a shared access policy and using a user-assigned managed identity. Memory tip: think “MIMIC” for Managed Identity, Managed Identity (user), and Connection string—the three ways to connect without hardcoding secrets.
This AZ-204 practice question tests your understanding of develop azure compute 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 THREE are valid ways to authenticate an Azure Functions app to an Azure Service Bus namespace?
Using an Azure AD token obtained via DefaultAzureCredential
Token-based authentication.
Using a connection string with shared access policy
Connection string includes key.
Using a system-assigned managed identity
Managed identity can be assigned to function.
Using a client certificate
Why wrong: Not supported for Service Bus.
Using a SAS key stored in code
Why wrong: SAS key is not recommended; connection string is used.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Using an Azure AD token obtained via DefaultAzureCredential
Option A is correct because DefaultAzureCredential from the Azure Identity library can authenticate to Azure Service Bus using Azure AD tokens. This credential chain attempts multiple authentication sources (environment variables, managed identity, Visual Studio, etc.) to obtain a token, which is then used to authorize requests to the Service Bus namespace via Azure RBAC.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Using an Azure AD token obtained via DefaultAzureCredential
Why this is correct
Token-based authentication.
Related concept
Read the scenario before looking for a memorised answer.
Using a connection string with shared access policy
Why this is correct
Connection string includes key.
Related concept
Read the scenario before looking for a memorised answer.
Using a system-assigned managed identity
Why this is correct
Managed identity can be assigned to function.
Related concept
Read the scenario before looking for a memorised answer.
Using a client certificate
Why it's wrong here
Not supported for Service Bus.
Using a SAS key stored in code
Why it's wrong here
SAS key is not recommended; connection string is used.
Common exam traps
The trap here is that candidates might think client certificates are a valid authentication method for Service Bus, but Service Bus only supports Azure AD, SAS tokens, and connection strings—not certificate-based authentication.
Detailed technical explanation
Under the hood, DefaultAzureCredential uses a chain of token credential providers (e.g., EnvironmentCredential, ManagedIdentityCredential, AzureCLICredential) that each attempt to acquire an OAuth 2.0 access token for the Service Bus resource URI (https://servicebus.azure.net). The token is then passed in the Authorization header as a Bearer token. In real-world scenarios, using managed identities (system-assigned or user-assigned) is preferred for Azure-hosted Functions to avoid managing secrets entirely, while DefaultAzureCredential is ideal for local development.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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Develop Azure compute solutions — study guide chapter
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FAQ
Develop Azure compute solutions — This question tests Develop Azure compute solutions — Read the scenario before looking for a memorised answer..
The correct answer is: Using an Azure AD token obtained via DefaultAzureCredential — Option A is correct because DefaultAzureCredential from the Azure Identity library can authenticate to Azure Service Bus using Azure AD tokens. This credential chain attempts multiple authentication sources (environment variables, managed identity, Visual Studio, etc.) to obtain a token, which is then used to authorize requests to the Service Bus namespace via Azure RBAC.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This AZ-204 practice question is part of Courseiva's free Microsoft 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 AZ-204 exam.
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