SOA-C02 Deployment, Provisioning, and Automation Practice Question
A SysOps administrator is troubleshooting a failed AWS CloudFormation stack creation. The stack includes an Amazon RDS DB instance with a custom DB parameter group. The error message states: 'The following resource(s) failed to create: [DBParameterGroup].' The administrator checks the CloudFormation template and sees that the DBParameterGroup resource has a property 'Parameters' with a list of parameters. What is the MOST likely reason for the failure?
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 parameter group is configured with parameters that are not compatible with the DB engine version.
Custom DB parameter groups must be configured with parameters that are compatible with the DB engine and version specified for the RDS instance. If the parameter group includes parameters that are not supported by the chosen engine version, the stack creation will fail with an error for the DBParameterGroup resource. In this case, the most likely cause is that one or more parameters in the 'Parameters' list are incompatible with the DB engine version. Option B is correct. Option A is incorrect because parameter group names can contain letters, numbers, and hyphens; they are not restricted. Option C is incorrect because the DB subnet group is not related to parameter group creation failure. Option D is incorrect because RDS does not require a VPC endpoint to create a parameter group.
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 parameter group name contains invalid characters.
Why it's wrong here
DB parameter group names are restricted to 1–255 alphanumeric characters, hyphens, and underscores. If a name contained an invalid character, AWS CloudFormation or the RDS API would reject it during template validation with a client-side error, before any DB instance creation attempt. The failure described is happening at instance provisioning time, which points to a semantic engine-compatibility problem rather than a syntactic name validation issue.
- ✓
The parameter group is configured with parameters that are not compatible with the DB engine version.
Why this is correct
When you associate a custom DB parameter group with a new DB instance, RDS verifies that the parameter group's family matches the target engine and version, and that every parameter value is valid for that engine. If the parameter group was created for a different engine version (e.g., a MySQL 5.7 group attached to MySQL 8.0) or contains parameters that were removed/renamed in the target version, RDS aborts the creation with an error referencing the parameter group. This is the most common cause of a failed launch when the parameter group name, subnet group, and network configuration are otherwise correct.
- ✗
The DB subnet group specified for the DB instance does not exist.
Why it's wrong here
A missing DB subnet group produces a distinct error such as 'DBSubnetGroup does not exist' or a similar VPC-related failure during provisioning. The problem in this scenario is explicitly tied to the DB parameter group, not to where the instance is placed. RDS creates and validates the parameter group association independently of subnet or VPC configuration, so an invalid subnet group would not generate a message about parameter compatibility.
- ✗
The VPC does not have an RDS VPC endpoint enabled.
Why it's wrong here
Amazon RDS does not require a VPC endpoint to create DB parameter groups or launch DB instances. VPC endpoints are used for private, network-level access to the RDS API and do not participate in parameter validation or engine compatibility checks. If a VPC endpoint were missing, you might see network or authorization errors when calling the RDS API from within the VPC, but the creation failure would not be caused by the parameter group's contents or family. This option confuses a networking convenience feature with the configuration validation that RDS performs at instance creation time.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SOA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SOA-C02 exam.