Mistake 1: Confusing similar Azure services
AZ-900 tests your ability to pick the right service for a scenario, and several services sound similar but solve different problems. Azure Functions versus Logic Apps versus Azure Automation is a classic trap — all three "automate" things, but Functions runs code on triggers, Logic Apps orchestrates workflows visually with connectors, and Automation runs scheduled or event-driven runbooks.
Similarly, Azure Policy versus Role-Based Access Control (RBAC) trips up many candidates — Policy controls what configurations are allowed, RBAC controls who can do what. Confusing these two is one of the most common wrong-answer patterns on governance questions.
Mistake 2: Treating pricing models as one-size-fits-all
Candidates often assume there is a single "correct" pricing model without reading which factor the scenario actually prioritises. Reserved Instances save money for steady, predictable workloads. Spot pricing saves the most for interruptible workloads that can tolerate eviction. Pay-as-you-go suits unpredictable or short-term needs.
A scenario asking about a workload that runs 24/7 for three years wants Reserved Instances; a scenario about a batch job that can restart if interrupted wants Spot pricing. Reading for these specific signals — rather than defaulting to the cheapest-sounding option — is the actual skill being tested.
Mistake 3: Mixing up storage redundancy options
LRS, ZRS, GRS, and GZRS all protect data, but at different scopes, and the exam tests whether you know which protects against which failure. LRS protects against hardware failure within one datacentre. ZRS protects against a datacentre failure within one region. GRS protects against an entire regional disaster by replicating to a second region.
A question describing a company that needs to survive a regional outage is testing GRS or GZRS specifically — answering LRS or ZRS on that scenario is a very common and avoidable error.
Mistake 4: Overlooking identity and governance depth
Many candidates spend most of their study time on compute and storage services, since they feel more concrete, and under-prepare for the identity and governance domain. This is a mistake — Management and Governance makes up roughly a third of the exam.
Make sure you can confidently distinguish Microsoft Entra ID from on-premises Active Directory, explain what Conditional Access does versus Multi-Factor Authentication alone, and know the difference between a resource lock and an RBAC role assignment. These distinctions come up more often than their perceived importance suggests.
Mistake 5: Rushing scenario questions without identifying the real constraint
AZ-900 scenario questions typically embed one specific constraint that determines the correct answer — cost, availability, compliance, or performance — inside a paragraph of business context. Skimming past that constraint and picking the first technically-correct-sounding option is the most common way well-prepared candidates lose points.
Before selecting an answer, identify the single word or phrase driving the scenario: "lowest cost," "must remain available during a regional outage," "cannot leave the country" (data residency), or "must scale automatically." That phrase almost always eliminates two of the four options immediately.
Test yourself against these exact traps
Our mock exams include the service confusion pairs and governance scenarios covered above.