5Platform & cloud

• 5.1Virtualization & containers

  Covers how a hypervisor (Type 1 / Type 2) drives server virtualization and storage virtualization, the characteristics of containers (Docker), which share the OS kernel and start up fast and light, and the judgment involved in orchestrating many containers automatically with Kubernetes.

• 5.2Cloud service models & migration

  Covers choosing among IaaS/PaaS/SaaS, which differ in the division of responsibility between the customer and the cloud provider, selecting among public/private/hybrid cloud, and the migration-strategy judgment between lift and shift and re-architecting when moving an existing system to the cloud.

• 5.3Database architecture design

  Covers choosing between RDB, which emphasizes transactional consistency, and NoSQL, which emphasizes schema flexibility and horizontal scale; replication, which balances read performance with data protection; sharding, which raises write throughput via horizontal partitioning; and the judgment behind performance improvement and relaxed consistency via caching.

• 5.4Network architecture design

  Covers choosing between L7 load balancing, which inspects application-layer content to route traffic, and L4 load balancing, which routes quickly at the transport layer; CDN, which distributes content to edge locations; DNS, which handles the hierarchy and redundancy of name resolution; and design judgment for redundant paths and latency optimization during failures.