In distributed systems, independent physical machines linked across unreliable networks must agree on a sequence of state transitions despite packet loss, network partitions, and node crashes. This fundamental problem—Distributed Consensus—is the foundational bedrock of all modern cloud-native infrastructure, powering metadata coordinators (etcd, Consul), distributed SQL databases (CockroachDB, TiKV, YugabyteDB), and modern streaming brokers (Kafka KRaft).
This module deconstructs the theory and practical implementation of consensus through the lens of the Raft Consensus Algorithm (Ongaro & Ousterhout, 2014) and Replicated State Machine (RSM) architecture: how leaders are elected without split-brain, how logs are replicated safely across majorities, and how linearizable consistency is guaranteed under severe hardware failures.