How the interviewer opens it
“Design a platform that helps companies manage their commercial vehicles, assignments, and maintenance. The platform also receives telemetry from the vehicles.”
The prompt is vague on purpose. The first minutes are for you. Reduce the prompt to the core features and agree on the numbers before you draw.
What to clarify first
- Fleet size and telemetry volume
- Operator traffic and read-to-write ratio
- Telemetry content and delivery
- Assignments
- Maintenance rules
- Latency
- Consistency and availability
- Durability
- Retention
- Scope limits
The interviewer has the answers. In a SysRound round, Alex gives these answers, as a real interviewer does.
Scope of a strong answer
Core requirements
- Register vehicles and show their current operational state.
- Assign vehicles and drivers without conflicts.
- Accept vehicle telemetry and show recent history.
- Track maintenance dates, distance thresholds, service completion, and due alerts.
Usually out of scope
- Route optimization and automatic dispatch
- Future assignment reservations
- Remote vehicle control
- Cross-region failover
What interviewers ask about
- Telemetry delays and device changes
- Reports can repeat, arrive late, or come from a replaced device. Current position and lifetime distance require different update rules.
- Assignments and vehicle availability
- Assignments compete for both vehicles and drivers. Service transitions and delayed command responses create more races.
- Maintenance dates and distance
- Distance reports can skip thresholds. Calendar rules must work without telemetry, and service completion changes the meaning of later reports.
Common mistakes
- One status field mixes connectivity, assignment state, and maintenance state.
- The last received report overwrites newer vehicle state.
- A cache check serves as the only assignment conflict check.
- Every raw report enters the command database and competes with assignment transactions.
- Maintenance depends only on telemetry and misses calendar deadlines.
- The design accepts assignments during a long state delay without an explicit safety policy.
The bar by level
- Senior (L5/E5)
- Protects both vehicle and driver assignments. Defines device order, service cycles, command retries, and calendar checks. Explains durable intake, replay, and delayed-state behavior.
- Staff (L6+/E6+)
- Defines authority across telemetry and operational stores. Sets enforceable delay and recovery limits. Handles device replacement, tenant isolation, service races, and capacity during replay.