DP-300 Practice Question: Plan and configure high availability and disaster recovery
This DP-300 practice question tests your understanding of plan and configure high availability and disaster recovery. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
Availability group configuration:
AG1 (Synchronous commit)
- Primary replica: SQL1 (automatic failover)
- Secondary replica: SQL2 (automatic failover, readable secondary)
- Secondary replica: SQL3 (synchronous commit, manual failover, readable secondary)
Listener: listener1, port 1433
Error log on SQL1:
2025-03-15 15:00:00.00 spid31s The availability group 'AG1' is being restarted due to a failure. Error: 35201. A connection timeout has occurred.
2025-03-15 15:00:05.00 spid31s The local availability replica of availability group 'AG1' has transitioned from resolving role to primary role.
2025-03-15 15:00:10.00 spid31s The availability group 'AG1' is online.
Query on SQL1:
SELECT replica_server_name, role_desc, synchronization_health_desc, connected_state_desc FROM sys.dm_hadr_availability_replica_states
WHERE group_id = '...'
Results:
SQL1 | PRIMARY | HEALTHY | CONNECTED
SQL2 | SECONDARY | NOT_HEALTHY | DISCONNECTED
SQL3 | SECONDARY | HEALTHY | CONNECTED
Refer to the exhibit. After a brief outage, the availability group recovered. However, SQL2 shows NOT_HEALTHY and DISCONNECTED. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Availability group configuration:
AG1 (Synchronous commit)
- Primary replica: SQL1 (automatic failover)
- Secondary replica: SQL2 (automatic failover, readable secondary)
- Secondary replica: SQL3 (synchronous commit, manual failover, readable secondary)
Listener: listener1, port 1433
Error log on SQL1:
2025-03-15 15:00:00.00 spid31s The availability group 'AG1' is being restarted due to a failure. Error: 35201. A connection timeout has occurred.
2025-03-15 15:00:05.00 spid31s The local availability replica of availability group 'AG1' has transitioned from resolving role to primary role.
2025-03-15 15:00:10.00 spid31s The availability group 'AG1' is online.
Query on SQL1:
SELECT replica_server_name, role_desc, synchronization_health_desc, connected_state_desc FROM sys.dm_hadr_availability_replica_states
WHERE group_id = '...'
Results:
SQL1 | PRIMARY | HEALTHY | CONNECTED
SQL2 | SECONDARY | NOT_HEALTHY | DISCONNECTED
SQL3 | SECONDARY | HEALTHY | CONNECTED
A
The automatic failover policy requires a quorum that is not met.
Why wrong: Quorum issues would affect all replicas, not just SQL2.
B
The listener is not configured correctly for SQL2.
Why wrong: Listener configuration does not affect replica synchronization.
C
The secondary replica SQL2 has an incompatible database version.
Why wrong: Version incompatibility would prevent the replica from joining, but the error indicates a connection timeout.
D
The network connection between SQL1 and SQL2 is still down after the outage.
The connection timeout error and the DISCONNECTED state suggest network issues.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The network connection between SQL1 and SQL2 is still down after the outage.
The error 35201 indicates a connection timeout. SQL2 is configured for automatic failover and synchronous commit. After the restart, SQL2 remains disconnected and not healthy. This is likely because the network connectivity between SQL1 and SQL2 is still interrupted or there is a persistent issue. Since SQL3 is connected and healthy, the issue is specific to SQL2.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The automatic failover policy requires a quorum that is not met.
Why it's wrong here
Quorum issues would affect all replicas, not just SQL2.
✗
The listener is not configured correctly for SQL2.
Why it's wrong here
Listener configuration does not affect replica synchronization.
✗
The secondary replica SQL2 has an incompatible database version.
Why it's wrong here
Version incompatibility would prevent the replica from joining, but the error indicates a connection timeout.
✓
The network connection between SQL1 and SQL2 is still down after the outage.
Why this is correct
The connection timeout error and the DISCONNECTED state suggest network issues.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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 the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DP-300 NAT questions on configuration and troubleshooting.
Plan and configure high availability and disaster recovery — This question tests Plan and configure high availability and disaster recovery — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The network connection between SQL1 and SQL2 is still down after the outage. — The error 35201 indicates a connection timeout. SQL2 is configured for automatic failover and synchronous commit. After the restart, SQL2 remains disconnected and not healthy. This is likely because the network connectivity between SQL1 and SQL2 is still interrupted or there is a persistent issue. Since SQL3 is connected and healthy, the issue is specific to SQL2.
What should I do if I get this DP-300 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DP-300 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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