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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
Deep dive into distributed systems engineering, covering consensus protocols (Raft/Paxos), the CAP theorem, and vector clocks. 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: BChoose between consistency (C) or availability (A)
When network partitions occur, a distributed system must either reject writes/reads to maintain identical state (Consistency) or accept operations and risk divergent data (Availability).
Correct answer: ARandomized election timeouts for each candidate node
Raft uses randomized election timeouts (e.g., 150ms–300ms) so one node times out and initiates an election before others, avoiding split votes.
Correct answer: BWhen network disconnection causes distinct sub-clusters to each believe they are the legitimate leader
Split-brain occurs when a network partition cuts cluster communication, causing nodes on both sides to elect independent leaders and accept conflicting writes, risking corruption.
Correct answer: BThe exact causal relationship and concurrency between distinct distributed events
While Lamport timestamps provide total ordering, vector clocks maintain vector arrays that can differentiate whether two events are causally related or occurred concurrently.
Correct answer: BIf the coordinator crashes permanently after the prepare phase, participants must wait indefinitely for a decision
In 2PC, if participants vote 'yes' and the coordinator fails before broadcasting 'commit' or 'abort', participants cannot independently resolve the transaction and hold locks indefinitely.
Correct answer: BReaching agreement on a single value among a group of unreliable processors over an asynchronous network
Paxos guarantees safety and consensus among distributed nodes communicating over an asynchronous, lossy network, as long as a quorum of non-faulty nodes is reached.
Correct answer: AAll read and write operations appear to take place atomically at a discrete point in time between their invocation and completion
Linearizability ensures that every operation appears to execute atomically at a specific instant between its start and finish, matching the behavior of a single, central copy of data.
Correct answer: BBy utilizing TrueTime API, which leverages GPS receivers and atomic clocks to bound timestamp uncertainty
Google Spanner's TrueTime API provides bounded time uncertainty intervals backed by atomic clocks and GPS, allowing the database to assign monotonic commit timestamps globally.
Correct answer: ATo ensure that read and write operations intersect at least one up-to-date node by satisfying R + W > N
A quorum (strictly majoritarian, or configured such that Read quorum + Write quorum > Total nodes) guarantees that any successful read operation overlaps with at least one node containing the latest write.
Correct answer: BTo efficiently disseminate cluster membership, node state, and failure detection information peer-to-peer
Gossip protocols periodically exchange state metadata between random peer pairs, eventually diffusing cluster membership and node health across the entire network in O(log N) rounds.
Correct answer: AReaching consensus when nodes may not only fail or drop packets, but also send conflicting or malicious messages
The Byzantine Generals Problem models scenarios where actors can act maliciously or deceitfully (arbitrary/Byzantine faults), requiring algorithms like PBFT to guarantee consensus.
Correct answer: AA data structure that can be replicated across nodes and resolved concurrently without coordination or merge conflicts
CRDTs (operation-based or state-based) rely on mathematically commutative and idempotent operations, allowing concurrent updates across replicas to converge to the exact same state without locks.
Correct answer: BClock drift, network jitter, and leap seconds make physical clocks unreliable for strict global ordering
NTP cannot guarantee perfect physical clock synchronization due to network latency, virtualization skew, and clock drift, making reliance on wall-clock time risky for transactional ordering.
Correct answer: BTo distinguish between older, stale leadership reigns and current cluster states
Epoch/term numbers act as logical clocks, allowing nodes to identify and disregard outdated commands or heartbeats emitted by disconnected or partitioned former leaders.
Correct answer: BDuring a read query, the coordinator compares data versions from multiple replicas and asynchronously updates out-of-date nodes
When a client reads data with a high consistency level, the coordinator queries multiple replicas; if it detects stale data, it returns the latest version to the client and writes updates to the stale nodes.
Correct answer: BDeterministic consensus is impossible to guarantee in an asynchronous network if even a single process is subject to unannounced crash failure
The landmark 1985 FLP theorem proved that in a purely asynchronous network, no deterministic consensus protocol can guarantee both safety and liveness if even one node can crash.