AIF-C01 Fundamentals of Generative AI Practice Question
A company operates a customer support chatbot that uses Amazon Bedrock with a knowledge base sourced from an S3 bucket containing frequently updated product documentation. The knowledge base uses OpenSearch Serverless as the vector store and is configured to sync daily. The chatbot uses the RetrieveAndGenerate API with a custom Lambda function that applies a system prompt instructing the model to base answers solely on the retrieved context. After a major update to the product documentation, the IT team verifies that the data source sync completed successfully and the new chunks are present in the OpenSearch index. However, the chatbot continues to respond with outdated information. Further investigation reveals that the Lambda function includes a response caching mechanism using Amazon ElastiCache for Redis with a Time-To-Live (TTL) of 24 hours. The cache key is based on the user query. The team notes that no cache invalidation is performed after documentation updates. What is the most likely cause of the outdated responses?
⚠ Common exam trap
AIF-C01 often tests RAG troubleshooting by presenting a scenario where the data pipeline looks healthy, tempting candidates to blame retrieval parameters or IAM — when the real culprit is an application-layer cache returning stale responses.
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 ElastiCache cache is returning stale cached responses that contain the old information.
The Lambda function caches responses in ElastiCache for Redis with a 24-hour TTL keyed on the user query, and no invalidation occurs after documentation updates. Even though the knowledge base sync succeeded and new chunks are in OpenSearch, the chatbot returns the cached stale answer for any query previously cached. This is the classic cache-staleness failure mode.
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 ElastiCache cache is returning stale cached responses that contain the old information.
Why this is correct
The Lambda layer caches responses keyed by user query with a 24-hour TTL and performs no invalidation after syncs, so identical queries return pre-update answers from Redis even though OpenSearch holds fresh chunks. The retrieval layer is bypassed entirely.
- ✗
The 'maximum results' parameter in the RetrieveAndGenerate API is set to a value too low to retrieve the new chunks.
Why it's wrong here
Raising 'maximum results' only changes how many chunks are returned per query; the stem confirms the new chunks already exist in the OpenSearch index, so retrieval depth is not the constraint. It would matter if relevant chunks ranked below the cutoff, but here the cached answer is returned before retrieval occurs.
- ✗
The embedding model used by the knowledge base has not been retrained on the new documentation.
Why it's wrong here
Embedding models are pre-trained and are not retrained during knowledge base ingestion; the sync embeds new chunks using the existing model, and the stem confirms those chunks are indexed. Retraining would only be relevant when changing embedding models, which requires re-indexing, not routine documentation updates.
- ✗
The IAM role for the Lambda function lacks permissions to access the new S3 objects.
Why it's wrong here
The stem states the data source sync completed and the new chunks are present in the index, which requires successful S3 reads, so the Lambda role's S3 permissions are demonstrably sufficient. Missing S3 permissions would instead cause sync failures or stale index content, not cached responses.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This AIF-C01 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 AIF-C01 exam.