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OpenStem
@openstem · Joined Jul 2026
7420 public items8 groups
Quiz5 questions
What is a race condition?
AA bug where the outcome depends on the unpredictable timing/interleaving of threads accessing shared stateBAn exception thrown when a thread starts too fastCA compile-time error in multi-threaded codeDA deadlock between two locks
Software · L2 · Java: Concurrency Basics
@openstem
Software · L2 · Java: Concurrency BasicsQuiz5 questions
If both aria-labelledby and aria-label are present, which wins for the accessible name?
Aaria-labelledby takes priorityBaria-label always winsCWhichever comes first in the HTMLDNeither — visible text always wins
Software · L2 · HTML & CSS: Accessibility & Responsive CSS Check
@openstem
Software · L2 · HTML & CSS: Accessibility & Responsive CSS CheckQuiz5 questions
What signals a producer to slow down when writing to a stream?
ABackpressure — write() returns false once the buffer hits highWaterMarkBThe 'end' eventCA thrown TypeErrorDNothing — Node buffers unboundedly
Software · L2 · Node.js: Streams & HTTP Check
@openstem
Software · L2 · Node.js: Streams & HTTP CheckQuiz5 questions
In the OAuth authorization code flow, what does the client exchange for an access token?
AThe user's raw passwordBA short-lived authorization code, plus its client secret or PKCE verifierCThe refresh token onlyDNothing — access tokens are issued immediately on redirect
Software · L2 · Networking & HTTP: Auth & Protocols Check
@openstem
Software · L2 · Networking & HTTP: Auth & Protocols CheckQuiz5 questions
Which algorithm is provably optimal for minimizing average wait time, given known burst lengths?
AShortest Job FirstBRound RobinCPriority SchedulingDFirst-Come First-Served
Software · L2 · Operating Systems: Choosing a CPU Scheduling Algorithm
@openstem
Software · L2 · Operating Systems: Choosing a CPU Scheduling AlgorithmQuiz5 questions
You need to limit concurrent access to a pool of exactly 5 database connections. Which primitive fits?
ASemaphore (count = 5)BMutexCSpin lockDThread-local storage
Software · L2 · Concurrency: Choosing a Synchronization Primitive
@openstem
Software · L2 · Concurrency: Choosing a Synchronization PrimitiveQuiz5 questions
Why does containment happen before eradication in incident response?
AEradication is always faster, so it should come lastBIsolating the affected system stops ongoing damage while investigation continuesCContainment and eradication are the same stepDBecause backups must be restored first
Software · L2 · Security & Auth: Incident Response Basics
@openstem
Software · L2 · Security & Auth: Incident Response BasicsQuiz5 questions
Why does the Test stage run before Package/Publish?
ATests run faster after publishingBIt's cheaper to fail fast on broken code than to publish a bad artifact firstCPublishing requires test results as input dataDThere is no required order between the two
Software · L2 · Docker & Kubernetes: CI/CD Pipeline Stages
@openstem
Software · L2 · Docker & Kubernetes: CI/CD Pipeline StagesQuiz5 questions
Why do unit tests run before integration tests in the PR pipeline?
AIntegration tests can't run without unit tests existing firstBUnit tests are faster, so failing fast on them avoids wasting time on slower checksCUnit tests replace the need for integration testsDThere's no particular reason for the order
Software · L2 · Testing: CI Test Execution Strategy
@openstem
Software · L2 · Testing: CI Test Execution StrategyQuiz5 questions
You need to add caching to an expensive remote call, transparently, behind the same interface. Which pattern?
AProxyBAdapterCFacadeDBridge
Software · L2 · Design Patterns: Which Structural Pattern?
@openstem
Software · L2 · Design Patterns: Which Structural Pattern?Quiz5 questions
Which annotation maps 'many orders belong to one customer'?
A@ManyToOne on the Order entity's customer fieldB@OneToMany on the Order entityC@ManyToMany on both entitiesD@Entity on the Customer only
Software · L2 · Spring Boot: Data Access & Transactions
@openstem
Software · L2 · Spring Boot: Data Access & TransactionsQuiz5 questions
What does `on FormatException catch (e)` do differently from a plain `catch (e)`?
AIt only catches FormatException (and subtypes), letting other errors propagateBIt catches every possible error typeCIt silently ignores the error without running any codeDIt only works inside async functions
Software · L2 · Dart: Error Handling & Testing
@openstem
Software · L2 · Dart: Error Handling & TestingQuiz5 questions
What does `http.get(Uri.parse(url))` return?
AA Future<Response> that completes with a status code and bodyBThe decoded JSON directlyCA Stream of response chunksDNothing — it must be awaited inside a StreamBuilder
Software · L2 · Flutter: Networking & Data
@openstem
Software · L2 · Flutter: Networking & DataQuiz5 questions
When does middleware.ts run relative to a matched route?
ABefore the route's page or route handler code executesBAfter the page has already renderedCOnly when the route throws an errorDOnly during the production build, never at request time
Software · L2 · Next.js: Middleware & Edge Runtime
@openstem
Software · L2 · Next.js: Middleware & Edge RuntimeQuiz5 questions
What does a `useFactory` provider let you do that `useClass` doesn't?
ACompute the provided value at runtime, optionally injecting other providersBSkip dependency injection entirelyCRegister the provider globally by defaultDAvoid needing an injection token
Software · L2 · NestJS: Modules, Providers & Pipes Check
@openstem
Software · L2 · NestJS: Modules, Providers & Pipes CheckQuiz5 questions
What does a MongoDB secondary replicate from the primary?
AThe oplog (operation log)BA nightly mongodump backupCThe query planner cacheDThe connection pool
Software · L2 · MongoDB: Replica Sets & Failover
@openstem
Software · L2 · MongoDB: Replica Sets & FailoverQuiz5 questions
What does a Postgres standby replay to reconstruct the primary's data?
AThe Write-Ahead Log (WAL)BA daily pg_dump backupCThe query planner's cacheDThe client's connection log
Software · L2 · PostgreSQL: Replication & High Availability
@openstem
Software · L2 · PostgreSQL: Replication & High AvailabilityQuiz5 questions
Which service orchestrates the overall CI/CD workflow across stages?
ACodePipelineBCodeBuildCCodeDeployDCloudFormation
Software · L2 · AWS: CI/CD Pipelines
@openstem
Software · L2 · AWS: CI/CD PipelinesQuiz5 questions
Which service compiles code, runs tests, and builds container images on GCP?
ACloud BuildBArtifact RegistryCCloud DeployDCloud Monitoring
Software · L2 · Google Cloud: CI/CD & Deployment
@openstem
Software · L2 · Google Cloud: CI/CD & DeploymentQuiz5 questions
What problem does state locking specifically prevent?
ASlow terraform plan performanceBTwo concurrent applies corrupting or conflicting on the same stateCProvider version mismatchesDForgetting to run terraform init
Software · L2 · Terraform: Safe Applies with Remote State & Locking
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Software · L2 · Terraform: Safe Applies with Remote State & LockingQuiz8 questions
Which of these HTTP methods is idempotent but not safe?
AGETBPOSTCPUTDOPTIONS
Software · L3 · API Design & REST
@openstem
Software · L3 · API Design & RESTQuiz8 questions
In the cache-aside pattern, what happens on a cache miss?
AThe request fails immediatelyBThe application reads from the database and populates the cache for next timeCThe cache automatically fetches from the database without application involvementDThe stale cached value is returned anyway
Software · L3 · Caching Strategies
@openstem
Software · L3 · Caching StrategiesQuiz8 questions
Which of these disqualifies a function from being pure?
ATaking more than one argumentBReturning a new object instead of a primitiveCReading the current system time inside the function bodyDBeing called more than once in a program
Software · L3 · Functional Programming Concepts
@openstem
Software · L3 · Functional Programming ConceptsQuiz8 questions
When a backtracking regex engine fails to match after a greedy quantifier consumed input, what does it do?
AImmediately reports no match with no further attemptsBBacktracks, giving back characters one at a time and retrying the rest of the patternCRestarts the match from a random positionDSwitches to a lazy quantifier automatically
Software · L3 · Regular Expressions & Text Parsing
@openstem
Software · L3 · Regular Expressions & Text ParsingQuiz8 questions
What problem does GraphQL's single-endpoint, client-specified query model primarily solve compared to REST?
AIt removes the need for a schemaBOver-fetching and under-fetching, by letting the client ask for exactly the fields it needs in one requestCIt eliminates the need for authenticationDIt guarantees faster network transport than REST
Software · L3 · GraphQL API Design
@openstem
Software · L3 · GraphQL API DesignQuiz8 questions
What is the key behavioral difference between a message queue and a pub/sub topic?
AA queue delivers each message to exactly one consumer in a group; a topic delivers a copy to every subscriberBA queue is always slower than a topicCA topic never persists messagesDThere is no functional difference
Software · L3 · Message Queues & Event-Driven Communication
@openstem
Software · L3 · Message Queues & Event-Driven CommunicationQuiz10 questions
Which HTTP status code means 'a new resource was created'?
A200 OKB201 CreatedC204 No ContentD301 Moved Permanently
Software · L4 · HTTP & REST — 10 Q
@openstem
Software · L4 · HTTP & REST — 10 QQuiz10 questions
Average-case lookup time in a hash map?
AO(1)BO(log n)CO(n)DO(n log n)
Software · L4 · Time complexity — 10 Q
@openstem
Software · L4 · Time complexity — 10 QQuiz10 questions
Which clause filters rows AFTER aggregation?
AWHEREBHAVINGCGROUP BYDORDER BY
Software · L4 · SQL fundamentals — 10 Q
@openstem
Software · L4 · SQL fundamentals — 10 QQuiz10 questions
What is a race condition?
ATwo threads finishing at the same timeBA bug where the outcome depends on the relative timing or interleaving of concurrent operationsCA performance optimisation that speeds up parallel codeDA deadlock involving exactly two threads
Software · L4 · Concurrency & parallelism — 10 Q
@openstem
Software · L4 · Concurrency & parallelism — 10 Q