Designs cost money
Strong candidates remember that architecture has a budget. Mentioning cost shows business awareness, that you weigh dollars alongside latency and scale. The cheapest design that meets the requirements is often the right one.
Where the money goes
- Compute for servers and serverless invocations.
- Storage for data at rest, growing over time.
- Bandwidth especially egress out of the cloud.
- Managed services that trade money for less operational work.
Cost levers
- Tier storage so cold data lives on cheap archives.
- Cache to cut repeated compute and database load.
- Right size instances instead of over provisioning.
- Use spot or reserved capacity for predictable savings.
Balance, do not obsess
You are not writing a budget, just showing awareness. Tie cost to the requirements, noting for example that a feature used rarely should not run on expensive always on infrastructure. Acknowledge when paying more buys clearly better reliability.
Key idea
Treat cost as a real constraint, tiering storage and caching to meet requirements at the lowest sensible spend without sacrificing needed reliability.