DBS-C01 Management and Operations Practice Question
Exhibit
Refer to the exhibit. CloudWatch Logs Error: ``` 2025-03-15T10:30:00.000Z [ERROR] 2006: MySQL server has gone away ```
A database specialist sees the above error in the application logs for an Amazon RDS for MySQL DB instance. The application is a web server running on an EC2 instance. What is the most likely cause?
⚠ Common exam trap
Watch out — candidates often confuse connection timeout errors with authentication or query syntax errors, but the specific error message in the logs (e.g., 'Connection timed out' or 'Lost connection to MySQL server during query') directly points to network or timeout issues, not SQL or credential problems.
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
✓
The database connection timed out due to inactivity or network connectivity issues.
The error message in the application logs indicates a connection timeout, which occurs when the client (EC2 web server) cannot establish or maintain a TCP connection to the RDS MySQL DB instance within the configured timeout period. This is most commonly caused by network connectivity issues (e.g., security group rules, NACLs, route tables, or VPC misconfigurations) or prolonged inactivity that triggers the MySQL `wait_timeout` or `interactive_timeout` setting, causing the server to close the connection. Option C directly addresses this scenario, while the other options produce different error codes or symptoms.
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 database user password has expired.
Why it's wrong here
Expired passwords cause authentication errors.
- ✗
A user attempted to execute an invalid SQL query.
Why it's wrong here
Invalid queries produce syntax errors.
- ✓
The database connection timed out due to inactivity or network connectivity issues.
Why this is correct
Common cause of 'server has gone away'.
- ✗
The database instance has run out of disk space.
Why it's wrong here
Disk full causes write failures, not connection closure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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