The answer is a write-through cache using Amazon ElastiCache. This strategy ensures strong consistency by writing data to both the cache and the primary database within the same transaction, so any read immediately following a write will retrieve the most current value from the cache, eliminating the risk of stale data. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how caching strategies trade off performance for consistency, with write-through being the only option that guarantees the cached data is always synchronized with the source of truth. A common trap is choosing lazy loading, which only populates the cache on a cache miss and can serve outdated data until the next write. Remember the memory tip: “Write-through writes to both, so consistency is never loath.”
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
A company runs a critical Oracle database on Amazon RDS. The database has a large table that is frequently accessed by multiple applications. The team wants to implement caching to reduce the load on the database. The cached data must be strongly consistent with the database. Which caching strategy should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Write-through cache using Amazon ElastiCache
Write-through cache ensures that data is written to the cache and the database simultaneously, providing strong consistency. Lazy loading can lead to stale data. Read-only cache does not help with writes. Eventual consistency is not acceptable.
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.
✗
Eventual consistency with DynamoDB Accelerator (DAX)
Why it's wrong here
DAX is for DynamoDB, not Oracle RDS.
✗
Read-only cache with Amazon ElastiCache
Why it's wrong here
Read-only cache does not address write load consistency.
✓
Write-through cache using Amazon ElastiCache
Why this is correct
Write-through ensures data is written to cache and DB together, maintaining strong consistency.
Related concept
Static NAT maps one inside address to one outside address.
✗
Lazy loading with cache-aside pattern
Why it's wrong here
Lazy loading may serve stale data until the cache is updated.
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
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
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 DBS-C01 NAT questions on configuration and troubleshooting.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Write-through cache using Amazon ElastiCache — Write-through cache ensures that data is written to the cache and the database simultaneously, providing strong consistency. Lazy loading can lead to stale data. Read-only cache does not help with writes. Eventual consistency is not acceptable.
What should I do if I get this DBS-C01 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 DBS-C01 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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