AZ-305 Design data storage solutions Practice Question
You need to design a storage solution for a large-scale media streaming application. The application serves video files to users worldwide. The solution must minimize latency for end-users and optimize content delivery costs. Which Azure service combination should you use?
⚠ Common exam trap
It's easy for candidates to confuse Azure Front Door (a global load balancer with HTTP caching) with a full CDN, but for static video content, Azure CDN (or Azure Front Door's CDN profile) is the correct service because it provides dedicated edge caching and egress cost optimization, whereas Front Door's primary role is application acceleration and routing.
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
✓
Azure Blob Storage with Azure Content Delivery Network (CDN)
Azure Blob Storage is optimized for storing large, unstructured data like video files, and when paired with Azure Content Delivery Network (CDN), it caches content at edge nodes worldwide. This combination minimizes latency for global users by serving videos from the nearest point of presence (PoP) and reduces egress costs by offloading traffic from the origin storage to the CDN's distributed network.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Azure Cosmos DB with multi-region writes
Why it's wrong here
Azure Cosmos DB with multi-region writes is a globally distributed NoSQL database engineered for structured data with single-digit-millisecond reads and writes; it is not an object storage system designed to hold large video binaries. Storing media files would require embedding them as base64 or binary payloads, which exceeds Cosmos DB's document size limits (2 MB) and incurs excessive request-unit costs for every read/write. Multi-region writes improve low-latency database updates, but they do not solve the fundamental mismatch of blob-scale media distribution. Therefore, it cannot serve as a storage platform for large-scale media files.
- ✗
Azure NetApp Files with Azure Front Door
Why it's wrong here
Azure NetApp Files provides high-throughput NFS/SMB file shares for enterprise workloads such as VDI, HPC, and lift-and-shift Linux apps, but its pricing is per GiB per month and it lacks native HTTP range support for byte-range video requests from CDN edges. Pairing it with Azure Front Door—a global content delivery and web-application firewall service—does not create a cost-effective media path, because Front Door expects blob or web-origin endpoints and does not natively offload video files from NetApp shares. For large-scale media, the per-gigabyte storage cost and lack of tiered object lifecycle management make this combination uneconomical. The service is wrong for this workload.
- ✓
Azure Blob Storage with Azure Content Delivery Network (CDN)
Why this is correct
Azure Blob Storage is object storage designed for petabytes of unstructured data, making it ideal for hosting video files, with support for HTTP range requests, lifecycle tiering, and secure streaming via SAS or anonymous read-only containers. Azure Content Delivery Network (CDN) caches video content at point-of-presence (PoP) edge locations, so users receive low-latency playback and at the same time egress from the origin blob storage is reduced, lowering network transfer costs. Together they deliver scale-to-zero bandwidth, high availability, and cost-efficient global media distribution. This is the only option that matches both storage semantics and content acceleration needs.
- ✗
Azure Files with Azure File Sync
Why it's wrong here
Azure Files is a managed file share service exposing SMB/NFS to cloud and on-premises machines, and Azure File Sync extends it to cache shares on Windows Servers, but it is not built for delivering media to end users over HTTP(S). File shares lack native pay-per-play CDN integration that supports video byte-range requests; instead they are optimized for interactive file access and backup, not concurrent streaming at global scale. Additionally, Azure Files pricing per GiB for stored and synced data plus transaction costs makes it expensive for vast video libraries. Therefore, it is not an appropriate streaming media storage design.
Quick reference
Azure Blob Storage Tier Comparison
| Tier | Storage Cost | Retrieval Cost | Latency | Use Case |
|---|---|---|---|---|
| Hot | Highest | Lowest | Immediate | Active data, frequent reads |
| Cool | Lower | Higher | Immediate | Data accessed < once / month |
| Cold | Lower still | Higher | Immediate | Data accessed < once / quarter |
| Archive | Lowest | Highest + rehydration delay | Hours | Long-term compliance retention |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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