Consensus and Coordination Algorithms Questions

How independent nodes agree on shared state: Paxos and Raft, leader election, quorum reads and writes, distributed locks, coordination services such as ZooKeeper or etcd, and Byzantine fault tolerance for replicas that cannot be trusted. Covers split-brain avoidance, fencing tokens, and the cost of coordination on throughput and latency. Frames when consensus is required versus when it can be designed away.