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15541+ short questions with short answers, covering every category and sub-category on the site — no long articles to scroll through. Good for a fast recap before an exam, or a few minutes of daily practice.

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Computer Networks → Introduction to Computer Networks 40

What is leader election benefit
Single coordinator preventing conflicting operations
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What is a write-ahead log (WAL)
Recording changes before applying for crash recovery
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What is log-structured storage
Appending all writes to log for high write throughput
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What is LSM tree
Log-Structured Merge tree for efficient writes with compaction
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What is B-tree in databases
Balanced tree for efficient search reads and range queries
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What is consistent hashing used for
Distributing load and minimizing reshuffling when nodes join/leave
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What is sharding in databases
Horizontal partitioning of data across multiple database instances
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What is database replication lag
Delay between write on primary and availability on replica
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What is read replica used for
Scaling read operations without loading primary database
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What is database connection pooling
Reusing database connections to avoid connection overhead
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What is N+1 query problem
Executing N queries to fetch details after 1 query for list
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What is database indexing for
Speeding up data retrieval at cost of write overhead
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What is a composite index
Index on multiple columns together
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What is database vacuum
Reclaiming storage from deleted or updated rows
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What is database replication conflict
Same data modified differently on multiple nodes simultaneously
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What is Lamport logical clock purpose
Capturing event causality in distributed systems
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What is vector clock purpose
Tracking causality across multiple processes in distributed systems
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What is gossip protocol convergence
Eventually all nodes receive the same information
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What is phi accrual failure detector
Adaptive failure detection using historical heartbeat timing
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What is epidemic broadcast
Information spreading through random pairwise gossip
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What is anti-entropy in distributed systems
Periodically comparing and synchronizing state between nodes
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What is read repair in distributed storage
Fixing stale data detected during read operation
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What is hinted handoff in distributed systems
Temporarily storing writes for unavailable node to deliver later
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What is a quorum read in distributed systems
Reading from majority of nodes to get latest value
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What is sloppy quorum
Accepting writes to available nodes even if not all primary quorum nodes
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What is CRDTs
Conflict-free Replicated Data Types
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What is Zookeeper znode
Data node in Zookeeper hierarchical namespace
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What is Zookeeper watch mechanism
Notification when watched znode changes
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What is etcd revision
Global monotonic counter tracking all changes in cluster
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What is consensus in distributed systems
All nodes agreeing on same value or decision
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What is FLP impossibility result
Consensus impossible with one faulty process in async system
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What is PBFT
Practical BFT
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What is Tendermint
BFT consensus algorithm used in blockchains
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What is proof of authority
Consensus using trusted validators (private blockchains)
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What is smart contract
Self-executing code on blockchain triggered by conditions
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What is network function chaining (SFC)
Directing traffic through ordered sequence of service functions
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What is SRv6 SID format
128-bit IPv6 address: locator function argument
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What is segment routing source routing
Encoding path as stack of segments at ingress node
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What is TI-LFA coverage guarantee
100 percent
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What is BGP PIC edge
Pre-computing backup BGP path for fast failover
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