Question 300
An Azure Container Apps HTTP service already has ingress and a scaling rule, with minReplicas=1 and maxReplicas=2. Peak traffic drives it to two replicas and p95 response latency rises, while the containers are healthy. Which revision scaling change should administrators test to add capacity without changing hosting platforms?
Explanation
Correct Answer
Azure Container Apps uses HTTP scaling rules to respond to concurrent requests, constrained by the revision's minimum and maximum replica counts. The problem states the application has already reached maxReplicas=2 while serving heavy traffic; the healthy containers cannot add a third replica until that limit changes. Increase the maximum to a supported, capacity-tested value and evaluate the HTTP concurrentRequests target to align scale-out with measured p95 latency and costs. Validate resulting replica counts, backend capacity and cold-start tradeoffs under load. This is distinct from choosing Container Apps over ACI or configuring overnight scale-to-zero.
Incorrect Answers
Changing charts can reveal useful details about peak traffic, concurrency and response times, but it does not change how many replicas the Container Apps revision can create. The given rule is already at maxReplicas=2 during the high-latency period. If healthy instances are capacity-constrained, the administrator needs to evaluate a higher supported maximum and the HTTP concurrency target, then measure the result. New dashboards alone leave the binding scale ceiling intact, so they cannot supply the additional service capacity requested in the question.
A Service Bus scaler is designed to react to queue depth or another supported event source. The application in the question receives HTTP requests and has no stated Service Bus queue. Adding a queue trigger would not characterize the existing inbound HTTP concurrency or resolve a two-replica cap caused by the current HTTP scale configuration. Event-driven queue scaling is relevant to worker applications that actually consume such messages; this service instead needs measured adjustment of its HTTP rule and allowed replica maximum. Use the trigger that corresponds to the traffic actually described.
Valid image-pull credentials are necessary for new replicas to start, but the existing revision has two healthy running replicas and no image-pull errors. Replacing successful registry credentials cannot by itself raise the maximum replica count or change the HTTP concurrency threshold that determines scale-out. Credential investigation would be relevant for failing revision starts or authorization errors, neither of which is present in the scenario. The material symptom is peak requests encountering a capacity ceiling, not an inability to retrieve the container image.
Lowering minReplicas from one to zero may reduce idle charges when the application has no requests, but it does not increase the maxReplicas=2 ceiling already reached during peaks. It can also introduce cold-start considerations when traffic resumes. The question explicitly asks for additional capacity under a healthy but saturated two-replica revision, not lower idle cost. Keep the scaling goal separate from another practice scenario's idle scale-to-zero objective: this case requires raising the maximum and tuning HTTP thresholds based on observed demand, not changing only the floor.






Microsoft Azure Administrator (AZ-104) Practice Tests