Cost Blind Spot — Azure Administrator (AZ-104)
The architecturally correct answer was also the most expensive. The exam wanted the cost-optimized option that still meets requirements.
Maximum resilience and minimum cost are not the same question
Exam scenarios signal cost sensitivity with phrases like "minimize spend," "cost-effective," or "the team has a limited budget." Candidates acknowledge this and still select Premium tier services, multi-region active-active deployments, or dedicated hosts — because those options feel thorough. The exam is testing whether you hold the cost constraint as a first-order filter, not an afterthought. When the scenario adds cost to the requirements list, every option that ignores it is wrong regardless of its technical merits.
The Scenario
A company needs to generate thumbnails from user-uploaded images. You design a solution with Azure Kubernetes Service and GPU-enabled nodes for fast processing. The correct answer uses Azure Functions with a Consumption plan triggered by Blob Storage events — images are under 10MB, processing takes 2-3 seconds per image, and the scenario said "cost-optimize for variable upload volume." AKS with GPU nodes costs $1,000+/month in base compute even at idle. Functions at 100,000 executions/month costs under $2. The exam tests whether you recognize that "image processing" does not automatically mean "GPU compute."
How to Spot It
- •Azure Spot VMs give up to 90% savings over pay-as-you-go for fault-tolerant workloads. Batch rendering, data analysis, and dev/test environments are the canonical Spot workloads. If the scenario describes interruptible work, Spot VMs or Spot-enabled AKS node pools are the cost-optimized answer.
- •Azure Cosmos DB charges for provisioned RU/s even when idle. A database provisioned at 10,000 RU/s costs ~$580/month. If the scenario describes "occasional reads" or "variable traffic," serverless Cosmos DB (pay per RU consumed) or Azure SQL Serverless eliminates idle costs.
- •Azure Front Door Premium costs ~$330/month base. Azure CDN Standard costs ~$0.08/GB. For a static website serving 100GB/month, CDN costs $8 vs. Front Door at $330+. The exam tests whether you select the CDN tier that matches the traffic profile, not the one with the most features.
Decision Rules
Whether full-mesh VNet peering or hub-spoke VNet peering with UDRs better satisfies all-to-all connectivity for a growing VNet fleet when the dominant constraint is cost scaling.
Domain Coverage
Difficulty Breakdown
Related Patterns