Dunzo GraphQL Specialist Interview Preparation

No. A schema describes the API contract, not the caller’s permission. Put authorization in the business boundary and apply it consistently across resolver paths. The same record may be reachable through several fields, so test indirect access as well as the obvious query.

Check your understanding: Request another user’s record through both direct and nested fields.

Common trap: Protecting only one resolver for a shared resource.

Concept reference: GraphQL: authorization

A shared business-layer rule reduces divergence when the same operation is exposed through GraphQL, REST or background processing. Pass identity and resource context explicitly and keep the policy testable. Centralization still requires every entry point to call the boundary.

Check your understanding: Compare access decisions across two different API entry points.

Common trap: A central policy that some resolvers bypass.

Concept reference: GraphQL: authorization

A cache or loader that omits the caller’s access scope may reuse a result under the wrong identity. Scope it to the appropriate request or authorization boundary and validate permissions for the underlying resource. Test mixed identities and nested requests rather than only single-user happy paths.

Check your understanding: Run equivalent queries as two tenants with overlapping record identifiers.

Common trap: A global loader keyed only by a guessed record ID.

Concept reference: OWASP: authorization checks

First, identify technical constraints and define measurable service objectives. Next, trace a query from validated schema fields through resolver dependencies and authorization checks. Contrast architectural trade-offs across simplicity, correctness, maintainability and scale, explicitly mitigate the risk of old and new implementations disagree on an edge case, and confirm system stability using shadow-traffic comparison and an error-budget based cutover rule.

Common trap: Reaching for a specific library or framework before defining constraints, failure envelopes, and automated verification criteria.

Prioritise the failure mode exhibiting the highest user blast radius and lowest observability. Formulate an explicit containment boundary, implement idempotent retries with jitter, and establish an automated rollback threshold. Verify resilience through a compatibility contract, expand-and-contract rollout and rollback rehearsal.

Common trap: Relying on passive monitoring dashboards without defining explicit error-budget alerts, rollback triggers, and verified recovery procedures.

Structure the response using Context-Decision-Tradeoff-Result: articulate the business and technical constraints, compare viable alternatives, explain the implementation (trace a query from validated schema fields through resolver dependencies and authorization checks), and document the accepted trade-off. Provide concrete proof: a project example, measured result and repeatable verification step.

Common trap: Speaking only in high-level abstractions or team accomplishments without detailing your direct implementation decisions, trade-offs, and measured results.

Formulate a falsifiable hypothesis from observable telemetry before altering configurations. Then inspect the query plan, resolver timings, batch boundaries and field-level authorization. Isolate the defect to the smallest reproducible boundary, validate root cause with evidence, and confirm full resolution using queue-depth metrics, bounded retry behaviour and a recovery drill.

Common trap: Applying speculative fixes or restarting services blindly without establishing an observable signal connected to a falsifiable hypothesis.

Produce a schema compatibility test with resolver traces and a query-cost limit. Document baseline assumptions, technical mechanism (trace a query from validated schema fields through resolver dependencies and authorization checks), rejected alternatives, bounded failure envelopes, and deterministic pass criteria. Supply reproducible verification via a trace, a minimal reproduction and a regression test.

Common trap: Presenting architecture diagrams or slides lacking automated unit/integration tests, observable metrics, or automated rollback configurations.