AZ-204 Develop for Azure storage Practice Question
You need to securely transfer an on-premises database backup to Azure Blob Storage. The backup file is 500 GB. You have limited bandwidth (10 Mbps) and need the transfer to complete within 24 hours. What is the best solution?
⚠ Common exam trap
The trap here is that candidates may overlook the bandwidth calculation and assume AzCopy or ExpressRoute can handle the transfer within 24 hours, failing to recognize that even with a dedicated connection, the raw throughput is insufficient for 500 GB at 10 Mbps.
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
✓
Use Azure Data Box to physically ship the data to Azure.
Given the 500 GB backup file and a 10 Mbps bandwidth limit, the theoretical maximum transfer time over the internet is approximately 500 GB * 8 bits/byte / (10 Mbps) = 400,000 seconds ≈ 111 hours, far exceeding the 24-hour requirement. Azure Data Box is the best solution because it allows you to physically ship the data on a secure, ruggedized device, bypassing network constraints entirely and ensuring the transfer completes within the required timeframe.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Azure File Sync to replicate the backup to Azure Files.
Why it's wrong here
Azure File Sync is designed for continuous synchronization of on-premises Windows Server file shares with Azure Files, creating a local cache. While it ensures data consistency and uses the network, it is not optimized for a one-time, large-scale initial data transfer when network bandwidth is severely constrained. Furthermore, it targets Azure Files, which might not be the optimal storage solution for a database backup compared to Blob Storage, and its primary function is not to overcome insufficient network speed for bulk uploads.
- ✓
Use Azure Data Box to physically ship the data to Azure.
Why this is correct
Azure Data Box is a robust, secure physical appliance specifically engineered for offline data transfer of terabytes to petabytes of data into Azure Blob Storage or Azure Files. When on-premises network bandwidth is insufficient or unreliable for large datasets, physically shipping the encrypted device directly to an Azure datacenter completely bypasses network limitations, making it the most efficient and secure method for initial bulk data ingestion within a tight time requirement.
- ✗
Use AzCopy to copy the backup file directly to Blob Storage.
Why it's wrong here
AzCopy is a highly optimized command-line utility for high-performance data transfer to and from Azure Storage, including Blob Storage. However, its transfer speed is fundamentally limited by the available network bandwidth of the on-premises connection. If the existing 10 Mbps network link is insufficient to transfer a large database backup within the specified time, AzCopy, despite its efficiency, cannot overcome this physical network bottleneck, leading to unacceptably long transfer times.
- ✗
Set up an ExpressRoute connection and use AzCopy.
Why it's wrong here
Azure ExpressRoute establishes a private, dedicated connection between on-premises networks and Azure, bypassing the public internet. While ExpressRoute offers enhanced security, reliability, and potentially lower latency compared to internet-based connections, it does not inherently increase the underlying physical bandwidth of the on-premises network link. If the existing on-premises connection is limited to 10 Mbps, ExpressRoute will still be constrained by that same 10 Mbps, rendering it inadequate for transferring a large database backup within a tight time requirement.
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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