Core Alibaba Cloud Products
What to know
Map each workload to the right product family. ECS provides virtual machines with instance families tuned for compute, memory, or general use; pair with ESS (auto scaling) and SLB (Server Load Balancer) for elastic tiers. OSS is object storage for unstructured data with storage classes (Standard, Infrequent Access, Archive, Cold Archive) and lifecycle rules. NAS is shared file storage; EBS-style disks attach to ECS. VPC provides isolated networking with vSwitches, security groups, and route tables. RDS is managed relational database; PolarDB is a cloud-native, high-performance relational engine. ApsaraDB for Redis handles caching. CDN caches content at edge nodes.
Know the decision axes: structured vs unstructured, block vs file vs object, managed vs self-managed, and cost vs latency.
Traps
Questions bait you with near-misses. OSS is not a filesystem and does not mount like NAS. Security groups are stateful instance-level firewalls; network ACLs are stateless subnet-level. RDS is managed - you do not get OS access. Auto Scaling reacts to metrics, not to a manual schedule only (both exist, but know which the scenario implies).
Rule of thumb
Pick storage by access pattern: object for HTTP/API access at scale, file for shared POSIX access, block for a single instance's disk. Pick database by engine compatibility and scale needs.
Worked example
A media site serves images globally and must cut latency. Answer: store originals in OSS and front them with CDN; lifecycle rules move cold objects to Archive to cut cost.