Drills

Architecture scenarioHard~12 min

Test external dependency boundaries

Combines protocol stubs, contract checks, sandbox tests, and failure simulation without depending on live production services.

Coding problemMedium~25 min

Test stable pagination across timestamp ties

Walks API pages through equal sort values and verifies no duplicate or missing resource ids.

Coding problemEasy~15 min

Test validation through the ProblemDetails contract

Verifies status, content type, stable error extensions, and field errors for an invalid API request.

Debugging scenarioHard~12 min

Thread pool starvation in .NET APIs

Diagnose thread-pool starvation caused by blocking work, unbounded concurrency, or sync-over-async in .NET APIs.

Debugging scenarioHard~12 min

Thread pool starvation symptoms in an ASP.NET Core API

Diagnose an ASP.NET Core API that becomes slow because request threads are blocked or exhausted.

Comparison questionMedium~7 min

Timeout vs cancellation in .NET

Distinguish timeouts from cancellation and explain how to combine them around external calls and request handling.

Coding problemMedium~25 min

Trace an unexpected API error by correlation ID

Tests that an unexpected failure returns a safe correlation identifier and records the same value in structured logs.

Debugging scenarioEasy~7 min

Triage a .NET service with dotnet-counters

Uses live runtime and application counters to classify CPU, memory, GC, exception, request, and ThreadPool symptoms before deeper collection.

.NETASP.NET Core

Debugging scenarioMedium~10 min

Triage downstream dependency latency

Explains how to diagnose and mitigate a downstream dependency slowing the API through timeouts, retries, and degraded behavior.

.NETApplication InsightsASP.NET CoreOpenTelemetry

Debugging scenarioMedium~10 min

Triage queue backlog and consumer lag

Explains how to investigate queue age, backlog, worker health, poison messages, dependency failures, and safe catch-up.

.NETApplication InsightsASP.NET CoreAzure Service BusOpenTelemetry

.NETApplication InsightsASP.NET CoreOpenTelemetry

Turn incidents into regression guards

Explains post-incident review, root cause, contributing factors, action items, tests, alerts, runbooks, and ownership.

Coding problemMedium~25 min

Update one property without loading the entity

Attaches a key-only stub and marks one property modified for a narrow update while naming the rules this pattern bypasses.

.NETASP.NET CoreC#EF CoreSQL

Use a circuit breaker around an unhealthy dependency

Explains closed, open, and half-open behavior, failure classification, recovery probes, and the limits of circuit breakers.

.NETASP.NET Core

Use ASP.NET Core policies for authorization

Explains policy-based authorization, requirements, handlers, claims, capabilities, and resource-aware checks.

.NETASP.NET CoreJWT

Concept questionEasy~5 min

Use cache-aside for a read-heavy API endpoint

Explains the cache-aside pattern for read-heavy endpoints and how misses, TTLs, and source-of-truth reads fit together.

.NETASP.NET CoreRedisStackExchange.Redis

Concept questionHard~9 min

Use capacity, load shedding, and backpressure signals

Explains saturation signals and how systems shed, queue, throttle, or degrade before cascading failure.

.NETApplication InsightsASP.NET CoreAzure Service BusEF Core+4

Architecture scenarioMedium~10 min

Use correlation IDs and logging scopes in ASP.NET Core APIs

Use correlation IDs, structured logs, and logging scopes to make API failures traceable in production.

.NETASP.NET CoreEF CoreSQL

Use DbContext pooling without leaking request state

Uses EF Core context pooling only when reusable context state, tenant isolation, and underlying connection state are controlled and tested.

.NETASP.NET CoreEF CoreSQL

Use EF Core compiled queries on hot paths

Explains when EF Core compiled queries help, what they do not fix, and how to measure their value.

Debugging scenarioMedium~10 min

Use EF Core query tags and correlation for production debugging

Explains how query tags, request correlation, and telemetry help connect slow SQL back to code paths.

.NETApplication InsightsASP.NET CoreEF CoreSQL

.NETASP.NET CoreEF CoreSQL

Use ExecuteUpdate instead of loading entities for bulk changes

Explains when set-based EF Core updates are better than loading entities and where lifecycle behavior can differ.

Architecture scenarioHard~12 min

Use If-Match preconditions to prevent lost updates

Connects HTTP preconditions to atomic database concurrency checks and honest 412 or 428 API behavior.

.NETASP.NET Core

Comparison questionEasy~5 min

Use logs, metrics, and traces for API diagnosis

Explains the different diagnostic roles of logs, metrics, and traces during backend production issues.

.NETApplication InsightsASP.NET CoreOpenTelemetry