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Lessons (16)

• Resilience, Disaster Recovery and Multi-Region Design

  … Route 53 health checks with failover or latency routing, or Global Accelerator for fast failover without waiting for …

• Replication, Partitioning & Sharding

  … Monitor replica lag and promote only a safe, current replica during failover. Partitioning: one logical table, smaller pieces …

• Collaborative Document Editing & Real-Time Sync

  … Sequencer failover without split-brain - Each collab server holds a lease per doc shard in etcd and gets …

• Design a Reliable Notification System

  Deliver email, SMS, push and in-app messages with preferences, isolation, idempotency, provider failover and auditable states. The …

• AWS Databases: Choose the Right One

  … The standby supports failover and does not serve application reads. A Multi-AZ DB cluster is a different …

• Multi-Region and Disaster Recovery

  … and final order state Stronger replication or controlled failover; reconcile uncertain payments. Restaurant menus Serve regional cache; refresh …

• DynamoDB Modeling, RDS Scaling and Data Resilience

  … data in six copies across three AZs, and failover to a replica is usually faster. Read replicas are …

• Networking, DNS and Traffic Routing

  … retain its previous answer or an existing connection. Failover must include connection errors, retry behavior and healthy old …

• Extending Kubernetes: CRDs, Operators and Admission

  … provisioning, failover, backups, upgrades. Well-known operators: cert-manager, Prometheus Operator, CloudNativePG, Strimzi (Kafka), Argo CD, Crossplane. Build …

• Brokers, Replication & Durability

  … one fewer system to run, faster failover, and support for millions of partitions. Kafka 4.0 removed ZooKeeper …

• Topics, Partitions & Offsets

  … and memory on brokers<br/ ❌ Longer rebalances and failovers"] - Partitions = the maximum number of consumers in a group …

• Internals, Upgrades, Resilience and Interview Questions

  … Argo CD ApplicationSets, a service mesh or Cilium Cluster Mesh, global DNS for failover. - Practice restores. A backup …

• Scaling, Load Balancing & Rate Limiting

  … memory, but they reduce balancing quality and make failover painful. Prefer stateless instances with sessions in Redis or …

• AWS Interview Questions: Clear Answers

  … recovery Strong answer: multiple app copies and database failover reduce some outages, but corruption or deletion may propagate …

• Backend Design Scenarios

  … database writes, session state, replication lag and failover correctness must be designed first. After the event, scale in …

• Caching & Redis

  … You can use both. - Replication + Sentinel: automatic failover to a replica. - Redis Cluster: shards data across nodes using …