The answer is that both instances must be in the same generation (Gen5), both must have no user databases, and both must be in the same region. These three requirements ensure that the failover group can synchronize seamlessly, as Azure SQL Managed Instance uses the same hardware generation to guarantee consistent performance and compatibility during geo-replication, while empty databases prevent conflicts during the initial seeding process. On the DP-300 exam, this question tests your understanding of the strict prerequisites for failover groups, often appearing as a select-all-that-apply trap where candidates mistakenly think instances can be in different subnets or that the secondary can contain user databases. A common memory tip is to remember the "Three Gs": same Generation, no user databases, and same Geo-region.
DP-300 Practice Question: Plan and configure a high availability and disaster recovery environment
This DP-300 practice question tests your understanding of plan and configure a high availability and disaster recovery environment. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE are requirements for configuring a failover group for Azure SQL Managed Instance? (Select three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Both managed instances must have the same service tier
Options A, B, and C are correct. Both instances must be in the same generation and have empty databases (no user databases). Option D is incorrect because the instances can be in different subnets. Option E is incorrect because the secondary must be empty (no user databases).
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Both managed instances must have the same service tier
Why this is correct
Failover groups require matching service tiers (e.g., General Purpose).
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-300 question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related DP-300 subnetting questions on CIDR, address ranges, and subnet selection.
Plan and configure a high availability and disaster recovery environment — This question tests Plan and configure a high availability and disaster recovery environment — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Both managed instances must have the same service tier — Options A, B, and C are correct. Both instances must be in the same generation and have empty databases (no user databases). Option D is incorrect because the instances can be in different subnets. Option E is incorrect because the secondary must be empty (no user databases).
What should I do if I get this DP-300 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related DP-300 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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