Database Replication and High Availability Questions

Comprehensive coverage of database replication architectures, topologies, design tradeoffs, and operational practices used to achieve high availability and data durability. Candidates should understand replication models such as primary backup, master slave, multi master, cascading replication, and read replica topologies, and explain synchronous versus asynchronous modes and the tradeoffs between consistency, latency, throughput, and durability. Important areas include causes of replication lag and mitigation techniques such as parallel apply, batching, compression, flow control, and topology choices that reduce lag; conflict detection and resolution in multi master setups including version vectors, vector clocks, causal ordering, last writer wins, and application level reconciliation; and split brain scenarios with prevention techniques such as quorum voting, fencing, and membership management. The topic also encompasses automatic failover and leader election using consensus protocols, implications for recovery point objective and recovery time objective depending on replication choices, backup and restore interactions and snapshot consistency, read scaling versus write scaling limits, redundancy and clustering strategies, quorum and availability group design, capacity planning, network and storage considerations, monitoring and alerting metrics for replication health and lag, testing and rehearsing failover, automation of failover and promotion, and concrete examples and tools such as MySQL replication, PostgreSQL streaming replication, Galera cluster, distributed consensus implementations like Paxos and Raft, and cloud managed availability services.