AZ-204 Practice Question: Connect to and consume Azure services and third-party services
Your company uses Azure Service Bus topics and subscriptions to send order notifications. You notice that some messages are not being delivered to a subscription. The subscription has a SQL filter that matches messages with a 'region' property equal to 'EU'. You verify that the messages have 'region' set to 'eu' (lowercase). What is the most likely cause?
⚠ Common exam trap
A common mix-up: candidates assume SQL filters in Azure Service Bus are case-insensitive like many SQL databases, but they are actually case-sensitive by default, leading to the incorrect conclusion that the filter is working correctly when it is not.
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 SQL filter is case-sensitive and 'EU' does not match 'eu'.
The SQL filter in Azure Service Bus is case-sensitive by default. The filter condition 'region = ''EU''' requires an exact match, including case. Since the messages have 'region' set to 'eu' (lowercase), they do not satisfy the filter condition and are therefore not delivered to the subscription. This is the most likely cause of the missing messages.
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 SQL filter is case-sensitive and 'EU' does not match 'eu'.
Why this is correct
Azure Service Bus SQL filters evaluate conditions against message properties using a SQL-like syntax. By default, string comparisons within these filters are case-sensitive. Therefore, if a message property, such as 'Region', has a value of 'EU', a SQL filter condition like `Region = 'eu'` will evaluate to false because 'EU' and 'eu' are treated as distinct strings. This strict matching behavior prevents the message from being delivered to the subscription.
- ✗
The subscription is disabled.
Why it's wrong here
A disabled Azure Service Bus subscription is an administrative state that renders the subscription inactive. When a subscription is disabled, it ceases to receive any messages from the associated topic, regardless of any defined filters or the content of the messages. If the subscription were disabled, no messages would be delivered to it at all, which contradicts the scenario implying a specific message type is not being received due to a filter issue.
- ✗
The subscription has no filter defined.
Why it's wrong here
When an Azure Service Bus subscription is created without an explicitly defined filter, it defaults to using a `TrueFilter`. This `TrueFilter` is the most permissive filter type, ensuring that every message published to the topic is delivered to that subscription. Consequently, if no filter were defined, the message in question would have been successfully delivered to the subscription, making this option incorrect.
- ✗
The subscription has a correlation filter instead.
Why it's wrong here
Correlation filters in Azure Service Bus are designed for simpler property matching, primarily on system properties like `CorrelationId`, `SessionId`, or custom user properties. A key distinction is that string comparisons within correlation filters are case-insensitive by default. However, the problem statement explicitly specifies that a SQL filter is being used, which inherently has case-sensitive string comparisons, making the characteristics of a correlation filter irrelevant to the described issue.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.