How many questions are in this practice set?

This practice set contains 50 questions with detailed explanations.

System Design Interview Questions

Q: What topics does this practice cover?

It covers the key topics and question types for System Design Interview, including vocabulary, grammar, reading, and practical test skills.

Q: Are there explanations for every question?

Yes, every question includes a clear explanation so you can understand the correct answer and learn from mistakes.

Q: Can I save my progress and mistakes?

Your wrong answers, favorites, scores, and study streak are saved in your browser, so you can review them on the same device.

Q: What practice modes are available?

You can practice randomly, take a timed mock exam, filter by difficulty, type, and topic, search questions, and review wrong answers.

Question 1

Which component distributes incoming traffic across application servers?

Select an answer Load balancerAPI gateway onlyDatabase replicaMessage queue

Question 2

A load balancer that routes based on URL path and HTTP headers operates at which layer?

Select an answer Layer 2DNS layerLayer 4Layer 7

Question 3

What does horizontal scaling add?

Select an answer More RAM on one serverFaster diskMore serversLarger CPU

Question 4

What does vertical scaling add?

Select an answer More serversMore replicasMore CDN edgesMore power to one machine

Question 5

Which technique is best for reducing repeated expensive computations?

Select an answer CachingShardingReplicationRate limiting

Question 6

Which cache eviction policy removes the least recently used item first?

Select an answer RandomLRUFIFOLIFO

Question 7

Why place a CDN in front of static assets?

Select an answer Replace the databaseHandle authenticationReduce network latencyExecute business logic

Question 8

What is the primary purpose of DNS?

Select an answer Store user sessionsBalance database writesCache API responsesMap domain names to IP addresses

Question 9

Which consistency model guarantees that a read returns the latest committed write?

Select an answer Strong consistencyEventual consistencySession consistencyCausal consistency

Question 10

In the CAP theorem, what does the letter C stand for?

Select an answer CapacityConsistencyCachingConcurrency

Question 11

Which database scaling method splits rows across multiple servers?

Select an answer IndexingCachingShardingDenormalization

Question 12

Which index type is best for exact key lookups?

Select an answer B-tree full scanLinked listText indexHash index

Question 13

Read replicas mainly help which workload?

Select an answer Read-heavyWrite-heavySchema migrationData backup only

Question 14

Which component decouples producers from consumers?

Select an answer DNSMessage queueCDNLoad balancer

Question 15

Which pattern moves a long-running task out of the request path?

Select an answer Client polling onlyDatabase triggerAsync job queueSynchronous retry

Question 16

What is a dead-letter queue used for?

Select an answer Cache missesDNS lookupsLoad balancer health checksMessages that repeatedly fail

Question 17

What does at-least-once delivery guarantee?

Select an answer No message loss, possible duplicatesNo duplicatesExactly-once deliveryLowest latency

Question 18

An idempotency key helps prevent what?

Select an answer DNS failuresDuplicate side effectsSlow queriesCache misses

Question 19

Which API style maps HTTP verbs to resources?

Select an answer FTPSOAP onlyRESTSMTP

Question 20

Which HTTP status code means a resource was created?

Select an answer 200204404201

Question 21

Cursor pagination is more stable than offset pagination when what happens?

Select an answer Data changes during paginationData is staticCache is emptyRequests are slow

Question 22

Which mechanism limits abusive API clients?

Select an answer Read replicasRate limitingShardingCDN

Question 23

A token bucket is used for what?

Select an answer Distributing IDsIndexing dataControlling request rateStoring sessions

Question 24

Which storage is best for immutable large media files?

Select an answer Relational databaseIn-memory cacheSession storeObject storage

Question 25

Which system is well suited for low-latency session storage?

Select an answer RedisData warehouseHDFSBatch pipeline

Question 26

Which database type is best for graph relationships?

Select an answer Search indexGraph databaseKey-value storeColumnar store

Question 27

Which microservice property enables independent deployment?

Select an answer Single binaryMonolithic codeLoose couplingShared database

Question 28

Which component centralizes authentication, routing, and rate limiting?

Select an answer Database shardWorker queueObject storageAPI gateway

Question 29

What is a circuit breaker used for?

Select an answer Stopping calls to a failing serviceSpeeding up database queriesCaching HTMLGenerating IDs

Question 30

Why add jitter to retries?

Select an answer Simplify DNSAvoid thundering herdIncrease throughputReduce cache size

Question 31

Which telemetry type shows a request path across multiple services?

Select an answer Metrics onlyAlerting onlyDistributed tracingLog aggregation only

Question 32

Which metric best indicates service availability?

Select an answer Page viewsCache sizeQuestion countUptime percentage

Question 33

Which practice protects data in transit?

Select an answer TLSBase64 encodingObfuscationPlain HTTP

Question 34

Which pattern isolates failures between services?

Select an answer AdapterBulkheadSingletonFactory

Question 35

Which strategy handles traffic spikes automatically?

Select an answer Longer timeoutsSynchronous writesAutoscalingNo limits

Question 36

Which design improves disaster recovery?

Select an answer Single regionNo backupsLocal cache onlyMulti-region replication

Question 37

Which are load-balancing strategies?

Select an answer DNS-only routingRound-robinLeast connectionsIP hash

Question 38

Which are common cache layers in a web system?

Select an answer In-memory cacheDatabase query cacheRelational schemaCDN

Question 39

Which are database scaling techniques?

Select an answer Deleting indexesShardingRead replicasPartitioning

Question 40

Which are message queue features or guarantees?

Select an answer Ordering per partitionInfinite storageAt-least-once deliveryDead-letter queues

Question 41

Which are API gateway responsibilities?

Select an answer AuthenticationRate limitingRoutingRunning migrations

Question 42

Which are observability pillars?

Select an answer TracesFeature flagsMetricsLogs

Question 43

A single database is usually enough for a global product at scale.

Select an answer TrueFalse

Question 44

Caching improves read latency but adds consistency complexity.

Select an answer TrueFalse

Question 45

Microservices should share one relational database by default.

Select an answer TrueFalse

Question 46

Exactly-once delivery is easy to guarantee in distributed messaging.

Select an answer TrueFalse

Question 47

Type the protocol that encrypts web traffic.

Select an answer

Question 48

Type the cache eviction policy that removes least recently used items first.

Select an answer

Question 49

Match each design concern to the technique that addresses it.

High read loadRepeated slow queryFailed messagesAbusive clients

Question 50

Match each consistency term to its meaning.

Strong consistencyEventual consistencyPartition toleranceAvailability

Which component distributes incoming traffic across application servers?

A load balancer that routes based on URL path and HTTP headers operates at which layer?

What does horizontal scaling add?

What does vertical scaling add?

Which technique is best for reducing repeated expensive computations?

Which cache eviction policy removes the least recently used item first?

Why place a CDN in front of static assets?

What is the primary purpose of DNS?

Which consistency model guarantees that a read returns the latest committed write?

In the CAP theorem, what does the letter C stand for?

Which database scaling method splits rows across multiple servers?

Which index type is best for exact key lookups?

Read replicas mainly help which workload?

Which component decouples producers from consumers?

Which pattern moves a long-running task out of the request path?

What is a dead-letter queue used for?

What does at-least-once delivery guarantee?

An idempotency key helps prevent what?

Which API style maps HTTP verbs to resources?

Which HTTP status code means a resource was created?

Cursor pagination is more stable than offset pagination when what happens?

Which mechanism limits abusive API clients?

A token bucket is used for what?

Which storage is best for immutable large media files?

Which system is well suited for low-latency session storage?

Which database type is best for graph relationships?

Which microservice property enables independent deployment?

Which component centralizes authentication, routing, and rate limiting?

What is a circuit breaker used for?

Why add jitter to retries?

Which telemetry type shows a request path across multiple services?

Which metric best indicates service availability?

Which practice protects data in transit?

Which pattern isolates failures between services?

Which strategy handles traffic spikes automatically?

Which design improves disaster recovery?

Which are load-balancing strategies?

Which are common cache layers in a web system?

Which are database scaling techniques?

Which are message queue features or guarantees?

Which are API gateway responsibilities?

Which are observability pillars?

A single database is usually enough for a global product at scale.

Caching improves read latency but adds consistency complexity.

Microservices should share one relational database by default.

Exactly-once delivery is easy to guarantee in distributed messaging.

Type the protocol that encrypts web traffic.

Type the cache eviction policy that removes least recently used items first.

Match each design concern to the technique that addresses it.

Match each consistency term to its meaning.

Course

Latest question banks