VA-003 Compare and configure secrets engines Practice Question
An administrator enables the database secrets engine for PostgreSQL. After configuring the connection, running `vault write database/config/someconfig` yields error: 'x509: certificate signed by unknown authority'. What is the most likely cause?
⚠ Common exam trap
HashiCorp often tests the distinction between TLS errors related to the target server's certificate (outbound connection) versus the Vault server's own certificate (inbound connection), causing candidates to confuse the direction of the TLS handshake.
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 PostgreSQL server's TLS certificate is not trusted by Vault's CA bundle
The error 'x509: certificate signed by unknown authority' indicates that Vault, when connecting to the PostgreSQL database, received a TLS certificate from the server that was not signed by any Certificate Authority (CA) present in Vault's trusted CA bundle. Vault uses its system's CA pool or a custom CA bundle configured in the connection string to verify the database server's certificate. If the PostgreSQL server uses a self-signed certificate or one issued by an internal CA not trusted by Vault, this error occurs. Option B correctly identifies that the PostgreSQL server's TLS certificate is not trusted by Vault's CA bundle.
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 connection string is incorrect
Why it's wrong here
An incorrect connection string would cause a connection timeout or refused, not a certificate error.
- ✓
The PostgreSQL server's TLS certificate is not trusted by Vault's CA bundle
Why this is correct
Vault must trust the database server's certificate; otherwise x509 error occurs.
- ✗
The database engine is not enabled
Why it's wrong here
If not enabled, the write would fail with 'no secrets engine mounted at path'.
- ✗
The Vault server's TLS certificate is self-signed
Why it's wrong here
That would affect client-to-Vault TLS, not Vault-to-database TLS.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This VA-003 practice question is part of Courseiva's free HashiCorp 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 VA-003 exam.