The answer is system-assigned managed identity and connection strings with account key. Managed identity works by securely assigning an Azure AD identity to your function app, allowing it to authenticate directly to Azure Storage without storing any credentials in code or configuration. Connection strings, on the other hand, use a shared account key embedded in the connection string to grant full access to the storage account. On the AZ-204 exam, this question tests your understanding of identity-based versus key-based authentication, and a common trap is selecting SAS tokens, which are for delegated, time-limited access rather than the function’s own identity. Remember that Azure AD tokens are used under the hood with managed identity, not passed directly, and certificate authentication is not supported for Storage. Memory tip: think “MI or Key” — Managed Identity for secure, credential-free access, or Connection String with Account Key for simpler, less secure setups.
AZ-204 Practice Question: Connect to and consume Azure services and third-party services
This AZ-204 practice question tests your understanding of connect to and consume azure services and third-party services. 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 authentication mechanisms can be used to authenticate an Azure Function to Azure Storage?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Storage account connection string with account key
Options A and D are correct. Managed identity and connection strings with account key are supported. Option B is wrong because SAS tokens are for delegated access, not function identity. Option C is wrong because certificate authentication is not supported for Storage. Option E is wrong because Azure AD token is used with managed identity, not directly.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Client certificate
Why it's wrong here
Client certificates are not used for Storage authentication.
✗
Shared access signature (SAS) token
Why it's wrong here
SAS tokens are for client access, not for the function's identity.
✓
Storage account connection string with account key
Why this is correct
Connection strings with account key are a supported method.
Related concept
Static NAT maps one inside address to one outside address.
✗
Azure AD token acquired via client credentials flow
Why it's wrong here
Azure AD tokens can be used but are typically obtained via managed identity.
✓
System-assigned managed identity
Why this is correct
Managed identity can be used to authenticate to Storage.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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-204 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related AZ-204 NAT questions on configuration and troubleshooting.
Connect to and consume Azure services and third-party services — This question tests Connect to and consume Azure services and third-party services — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Storage account connection string with account key — Options A and D are correct. Managed identity and connection strings with account key are supported. Option B is wrong because SAS tokens are for delegated access, not function identity. Option C is wrong because certificate authentication is not supported for Storage. Option E is wrong because Azure AD token is used with managed identity, not directly.
What should I do if I get this AZ-204 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related AZ-204 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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