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Ready-made multiple-choice practice quizzes, hand-checked. Take any free quiz online — every answer comes with an explanation, and every quiz page has a full answer key to revise from.
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Free · no sign-up · no time limit
Ready-made multiple-choice practice quizzes, hand-checked. Take any free quiz online — every answer comes with an explanation, and every quiz page has a full answer key to revise from.
IT
Assess your understanding of indexing internals, storage engines, isolation levels, NoSQL scaling, and vector indexing. Answer each question to see whether you got it right, with an explanation every time.
A free 16-question multiple-choice practice test on IT. Each question has one correct answer and a short explanation, and the full answer key below the player doubles as a study sheet. No account, no time limit — take it as often as you like.
This is a free, 16-question multiple-choice quiz. Answer each question to see whether you got it right, with an explanation for every answer. There is no sign-up and no time limit — take it as many times as you like, and use the answer key above to revise before or after.
Correct answer: AB+ Trees store all actual record pointers in leaf nodes linked sequentially, making range scans efficient
In a B+ Tree, non-leaf nodes store only keys for navigation, while all actual data/pointers reside in sequentially linked leaf nodes, making range traversals fast.
Correct answer: BIt buffers writes sequentially in memory (MemTable) before flushing immutable SSTables to disk sequentially
LSM-Trees append writes sequentially to a write-ahead log and an in-memory MemTable, avoiding expensive in-place random updates by batching and flushing sorted SSTables sequentially.
Correct answer: CPhantom Reads
Repeatable Read guarantees that read rows do not change between queries, but concurrent transactions can still insert new matching rows that appear in subsequent scans (Phantom Reads).
Correct answer: BReaders do not block writers, and writers do not block readers, by maintaining multiple row snapshots
MVCC tracks transaction IDs on rows to present consistent historical snapshots, allowing readers to view stable states without acquiring read locks that block concurrent writes.
Correct answer: BIt partitions vector space into Voronoi cells via clustering to narrow the search scope for approximate nearest neighbors
IVF partitions high-dimensional vector spaces into clusters using k-means; queries are compared only against centroids and vectors within the closest centroids, accelerating searches.
Correct answer: ADecomposing high-dimensional vectors into smaller sub-vectors and quantizing them to drastically reduce RAM usage
Product Quantization slices vectors into lower-dimensional sub-vectors and represents them with compact centroid codes, shrinking vector memory footprints by 80-95%.
Correct answer: BThe total number of nodes across the cluster that store copies of a specific row partition
The replication factor defines how many physical cluster nodes will maintain copies of a given partition key across the ring topology.
Correct answer: BSubstantially increased write latency due to blocking on physical disk rotational/flash flushes
Calling fsync() on every transaction forces data out of volatile OS caches to non-volatile disk media, ensuring durability (ACID) at the cost of disk write latency.
Correct answer: BAn index that contains all columns requested by a specific query, eliminating the need to read the base table heap
A covering index contains all the columns needed to resolve a query (via indexed or included columns), allowing the engine to return results purely from the index tree without fetching heap pages.
Correct answer: BSystem crashes and power loss before modified dirty pages in the buffer pool are written to data files
The WAL logs all changes sequentially to durable storage before dirty in-memory buffer pool pages are flushed; on recovery, the database replays the log to restore consistency.
Correct answer: B'w: 1' acknowledges writes as soon as the standalone primary writes to memory, risking data loss during failovers
'w: 1' acknowledges as soon as the primary node writes (often in memory), risking rollbacks if the primary crashes before replicating; 'w: majority' requires a majority of replicas to acknowledge.
Correct answer: BThe amount of physical data written to disk relative to the logical data size of the original write operation
Write amplification measures how many bytes are physically written to durable storage relative to the logical payload; high amplification occurs during B-Tree splits and LSM-Tree compactions.
Correct answer: BTo rapidly verify whether an SSTable definitely does not contain a specific key without performing disk I/O
Bloom filters are probabilistic in-memory data structures that can definitively confirm if a key is absent from an on-disk SSTable, sparing unnecessary disk seek operations.
Correct answer: BEmbedding enables fast, single-read retrievals but risks update anomalies and document size growth; referencing avoids duplicates but requires multi-query joins
Embedding co-locates related data for fast atomic reads but risks document size limits and update anomalies, whereas referencing avoids redundancy at the expense of application-level joins.
Correct answer: AExact k-NN calculates distances to every vector in the dataset (linear complexity); ANN uses heuristics to find close matches much faster
Exact k-NN computes distance across every single vector (brute-force linear scan, O(N)), which becomes unfeasible at scale; ANN trades 100% recall for fast sub-linear query execution using graph or clustered indexes.
Correct answer: BHorizontally partitioning a dataset across multiple independent database instances to scale beyond single-node compute and storage limits
Sharding splits massive datasets into partitions distributed across multiple separate database servers, enabling horizontal scaling when single-node vertical scaling limits are reached.