Systems Design Concepts Practice Test

These questions are part of the practice quiz. Start practicing

• Data migration in these systems typically occurs during what?
• Which relationship is implemented with a junction table containing foreign keys to both sides?
• Which statement best describes causal consistency?
• Modulo hashing can have drawbacks that ring-based hashing mitigates. Which of the following describes a drawback of modulo hashing?
• Which statement best describes a B-tree index in databases?
• How does GraphQL address over-fetching and under-fetching in data retrieval?
• Which option reflects availability-oriented choices in distributed databases?
• What are typical specifications of a single app server in modern practice?
• For write-heavy workloads, which database design is commonly preferred?
• What does the Taylor Swift concert ticket key illustrate about hot spots?
• What is the primary role of replication in distributed systems?
• In modern database capacity planning, when should you consider sharding?
• Which statement correctly describes horizontal and vertical partitioning?
• Which relationship describes associations where records on both sides can relate to multiple records on the other side?
• What best describes In-Process Caching?
• Which scenario is appropriate for eventual consistency?
• What is the purpose of an idempotency key in a payment API?
• In a Role-Based Access Control (RBAC) model, how are permissions granted?
• What is a common use case for a key-value store?
• What is a key benefit of consistent hashing compared to simple modulo hashing?
• What is the main implication of index storage cost?
• Geohash is described as a spatial indexing approach that converts 2D coordinates into a 1D string. Which statement about geohash is true?
• What is the purpose of the dataloader pattern in GraphQL?
• When a new node is added on the hash ring, which keys move?
• Which eviction policy removes the item not accessed for the longest time when the cache is full?
• Which statement best describes the recommended default API approach in system design interviews?
• What is the primary cost associated with not reusing HTTP connections across requests?
• Which statement best describes a Log-Structured Merge Tree (LSM Tree)?
• Which statement best describes a Hash Index?
• Which mitigation technique for cross-shard queries involves precomputation via background jobs?
• Which statement about Directory-Based Sharding is true?
• Why must the leftmost column in a composite index appear in the query for the index to be usable?
• Which statement best characterizes the benefit of range-based sharding for a multi-tenant SaaS where each tenant's users query their own range?
• Which latency figure is the cross-region latency range that informs decisions about data replication and edge caching?
• Which HTTP method should be used when updating a full resource profile rather than just a single field?
• In hash-based sharding, what happens when the shard count changes?
• In the Scale Trigger Decision Framework, what is a database scaling threshold?
• Which statement best describes REST resource modeling?
• Where would you typically apply strong consistency in a domain?
• What best describes a cache-as-denormalized layer?
• Which practice deliberately duplicates data to speed up reads at the cost of potential inconsistencies?
• Which load balancer type is recommended for WebSocket connections to preserve persistent TCP connections end-to-end?
• Why would a system use a denormalized pre-computed feed table indexed by viewer_id and created_at?
• What is the primary benefit of partitioning data and co-locating servers by region when users primarily interact with data in their own geography?
• What is the general purpose of database constraints such as NOT NULL, UNIQUE, and CHECK?
• Which statement best describes how shard keys influence cross-shard lookups?
• Which statement best describes HTTP POST semantics?
• What is the typical range of the hash ring used in consistent hashing?
• Quadtree is a spatial index that subdivides a region into four quadrants. Which statement about quadtrees is correct?
• Which recommendation avoids rushing to add a queue and suggests alternative optimizations first?
• Redis Cluster uses which hashing approach?
• Strong consistency guarantees what in a distributed system?
• Before proposing caching in a design interview, what should you do?
• In API design interviews, what is a recommended approach?
• Which technique helps prevent a cache stampede by preloading the cache before expiry?
• Which example illustrates eventual consistency?
• Which properties are included in ACID guarantees?
• What is a recommended approach to handle multi-shard operations without distributed transactions?
• When should you use a CDN?
• According to cache capacity guidelines, when should you scale the cache?
• CDNs use consistent hashing to determine which edge servers cache specific content to minimize misses when what happens?
• Which database type stores data as nodes and edges optimized for traversing relationships?
• What is the purpose of virtual nodes in a hash ring?
• What anti-pattern occurs when sharding by a timestamp routes all new writes to the most recent shard?
• Which scenario is best served by a Wide-Column Database?
• Which index type is typically used for full-text search?
• Which action is a recommended alternative to immediately adding a queue for write throughput improvements?
• WebRTC is almost exclusively used for what scenario?
• Which statement best describes the Request Body in HTTP requests?
• What best defines a covering index?
• Which pagination approach is more stable when new records are added during pagination?
• CH in product system design interviews should be discussed how?
• Why can't B-tree indexes efficiently support certain LIKE patterns?
• Which scenario is best suited for gRPC over REST?
• What RAM range do modern app servers have, and what is the first bottleneck?
• Which scenario most strongly favors using UDP over TCP?
• Availability guarantees which of the following?
• What is the primary purpose of an Inverted Index?
• Which sharding strategy assigns contiguous ranges of shard key values to specific shards, enabling efficient range scans but risking hot spots when traffic concentrates on a single range?
• Which statement best justifies using WebSockets?
• What is a Composite Index?
• What is the end-to-end latency when a single Kafka broker handles up to 1 million messages per second?
• Which use case is best served by SSE?
• What describes the cache invalidation on writes strategy?
• What is the effect of not using keep-alive or HTTP/2 multiplexing on HTTP requests?
• When a node fails or is removed, what happens to the keys it was responsible for?
• Which statement about the relationship between SQL databases and a key-value store is accurate?
• When is GraphQL particularly advantageous compared to REST?
• What is the typical SSD read latency for indexed queries?
• Which statement about GraphQL usage is correct?
• In RBAC, which description accurately reflects typical role permissions?
• Which set of HTTP methods are idempotent by design?
• What best characterizes a hot shard anti-pattern?
• What is Cache Consistency?
• Sharding is best used when?
• When a new node is added, which keys move?
• In an LSM-tree, what happens to new writes in terms of memtable and SSTable?
• What is a key weakness of simple modulo hashing when cluster size changes?
• What caching pattern is described as the default in caching strategies?
• Which pagination method uses an encoded pointer and next_cursor value to paginate results?
• GraphQL is considered when REST cannot meet needs. Which statement aligns with this guideline?
• Which statement best captures REST resource modeling practice?
• Why include jitter with exponential backoff?
• Which algorithm is recommended for SSE or WebSocket workloads?
• Which statement explains index write overhead on a table?
• Which statement best describes HTTP GET semantics?
• WebRTC is almost exclusively used for which scenario?
• What is the primary purpose of rate limiting in a system?
• R-Tree is typically used for which type of data?
• DynamoDB placement uses a variation for partitioning and performs what kind of rebalancing?
• Which statement describes Read-Your-Own-Writes consistency?
• Which sharding approach stores shard assignments in a lookup table and uses a directory before querying data, offering flexibility but adding latency and a potential single point of failure?
• Which index type is default recommended for most scenarios?
• What is a cross-shard query?
• Which mitigation is recommended for hot spots by isolating hot keys to dedicated shards?
• Which condition most clearly triggers the need to shard a database?
• In the context of consistent hashing, what does the hash ring represent?
• What HTTP status code is commonly returned when rate limits are exceeded?
• Which versioning approach uses URL paths like /v1/events and is the most common due to explicit routing?
• What is the primary speed advantage when considering sequential vs random disk access?
• What is External Cache (Redis) primarily used for?
• What is the primary function of load balancer health checks?
• Why might gRPC outperform REST in some benchmarks?
• Which description best defines eventual consistency in a distributed system?
• Which HTTP method updates only specified fields of an existing resource and is not guaranteed to be idempotent depending on implementation?
• Graph databases are typically avoided in interviews unless which query pattern is central to the application?
• Which statement best describes gRPC usage?
• What is the typical capacity and latency of a single Redis instance used for caching?
• Which design principle stores each piece of information in exactly one place to prevent anomalies?
• Which statement about TTL is true?
• For strong consistency, which database technologies are typically used in strong consistency mode?
• What is a practical mitigation for the hot key problem?
• Under what conditions is a simple single-instance architecture preferred?
• According to CAP, in a partitioned network you must choose between which two properties?
• What is the primary function of a CDN cache?
• Which statement best describes hash indexes in practice?
• Which statement about managed sharding is correct?
• Which scenario justifies proposing sharding?
• Which statement best describes RPC usage?
• What is a concise description of how GraphQL helps with data-fetching inefficiencies?
• What distinguishes partitioning from sharding?
• Do virtual nodes solve workload imbalance caused by hot keys?
• What conditions in the framework trigger cache scaling?
• For a user-centric app, which field typically serves well as a shard key?
• Which index type cannot efficiently support range queries?
• Why should you prefer system-generated IDs for primary keys instead of business data like emails?
• Which statement best describes a relational database (SQL)?
• What is the typical latency within a single availability zone?
• Which statement about HTTP status codes is correct?
• Which caching pattern writes data only to the cache and flushes it to the database asynchronously in the background?
• Which database type is optimized for massive write-heavy workloads and time-series data?
• Which statement accurately defines idempotence in HTTP requests?
• Which statement best captures when to shard?
• What is a characteristic of DNS-based client-side load balancing?
• Which sharding approach offers maximum flexibility for isolating hot users to dedicated shards but may introduce latency due to directory lookups?
• What is a composite index?
• Why are stateless services preferred for horizontal scaling?
• In read-through caching, what role does the cache play?
• Cross-shard queries are those that require data from multiple shards because the query does not align with the shard key. Which mitigation is commonly recommended?
• What is the effect of adding INCLUDE columns to an index (a covering index)?
• Which protocol guarantees cross-shard consistency but is slow and fragile, leading most production systems to avoid it?
• Which statement best describes Path Parameters versus Query Parameters?
• Denormalization is typically used in which scenarios?
• What does a GraphQL schema define?
• Which index type is typically chosen for general-purpose use because it supports both exact-match and range queries?
• A one-to-many relationship is modeled by placing a foreign key on which side?
• Which statement best describes access patterns in database design?
• What is the recommended approach to discussing CAP in system design interviews?
• What is the role of a Bloom filter in LSM-tree storage?
• Which scenario benefits most from write-behind caching?
• Which statement correctly distinguishes authentication from authorization?
• Which statement correctly reflects latency for simple indexed queries and caching guidance?
• What is true about high availability and sharding?
• What caching strategy is recommended for hot data before external caches?
• When should you scale your message queue infrastructure?
• Which pagination method breaks large result sets into pages by skipping a set number of records and can produce duplicates or skipped records if data changes during pagination?
• What is the role of the high-level design stage in the delivery framework?
• Which eviction policy removes the item with the lowest access count?
• What characterizes a document-oriented database?
• In circuit breaker terminology, what happens when the circuit is opened due to failures?
• If brief inconsistency would be catastrophic, which CAP property should you prioritize?
• Why can't B-tree indexes efficiently support certain LIKE patterns?
• What is the primary purpose of sharding in a database system?
• When should you choose WebSockets or Server-Sent Events (SSE)?
• In a composite index on (user_id, created_at), which query pattern is most efficiently served?
• Data modeling appears twice in the design process; when does it occur?
• Which statement best reflects how production systems typically handle cross-shard transactions?
• What explains cross-region latency in distributed systems?
• How can DNS be used to improve availability across data centers?
• At very large scale, some teams drop foreign keys and enforce integrity at the application layer.
• What best describes the GraphQL N+1 problem?
• Which statement best describes TTL (Time To Live) in caching?
• Which index is standard for precise spatial queries over points and polygons in production databases like PostGIS?
• Which algorithm is recommended for SSE or WebSocket workloads due to long-lived connections?
• What characterizes Write-Through caching?
• In a sharding interview strategy, after proving a single database cannot handle the load, what should you propose next?
• API keys are best suited for which scenario?
• Which statement about JSON Web Tokens (JWTs) is true?
• Which statement about horizontal partitioning is true?
• Which statement best describes REST API usage?
• What is the purpose of compaction in an LSM-tree?
• Which statement best captures per-feature CAP trade-offs in system design?
• Partition tolerance is defined as a system property that ensures what?
• What performance improvement is typical when using an External Cache like Redis?
• PostgreSQL automatically creates a B-tree when you add a primary key or unique constraint. True or False?
• Which statement about the REST request body is true?
• What is a Cache Stampede?
• Which is a core step in the five-step caching strategy?
• Which type of load balancer routes traffic based on URL or headers?
• Which status code indicates that authentication is required?
• Which caching pattern is more common with Redis for application-level caching?
• Which HTTP method replaces an entire resource with the provided data and is idempotent, making it suitable for updating a full user profile?
• Which property makes a good shard key?
• Which HTTP method is appropriate for canceling a booking and is idempotent?
• What is the recommended starting approach in a schema design interview?
• What is a typical trigger for horizontal scaling of application servers?
• What is a major downside of simple hash-based sharding without consistent hashing?
• Which HTTP method removes a resource and is idempotent because repeated calls leave the resource deleted?
• What is a fundamental issue with simple modulo hashing when the cluster size changes?
• Why would a system designer use per-feature consistency trade-offs?
• Which distribution technique minimizes data movement when shards are added or removed by placing shards on a virtual ring and assigning each key to the nearest shard clockwise?
• What does the circuit breaker pattern do in a microservices architecture?
• Which statement reflects a trade-off between GraphQL and REST?
• Which constraint enforces referential integrity by linking to another table's primary key?
• Which system uses consistent hashing with virtual nodes to distribute data across its ring?
• Why do separate B-tree indexes on latitude and longitude fail for proximity search?
• Which statement describes a RESTful system design characteristic?
• Which strategies are used to mitigate hot spots in consistent hashing?
• Which statement about sending data in requests is true?
• What best defines the hot key problem in caching?
• If Redis goes down, what technique helps prevent overwhelming the database?
• What term describes a shard that receives disproportionately more traffic than others, undermining sharding benefits?
• Which statement best describes GraphQL usage?
• What is a primary key in a relational database?
• Which statement best describes Protocol Buffers usage?