Key points

• Instance family should match the dominant compute, memory, storage, network, or acceleration bottleneck.
• Multi-AZ fleets require multiple instances, load balancing, and external durable state; one large instance remains one failure boundary.
• Roles, immutable images, patching, Auto Scaling, and observed rightsizing reduce security, drift, and idle-cost risk.

Best-known use cases

• Run applications needing OS-level control or long-lived servers.
• Use specialized instance capacity or software incompatible with functions/managed containers.

What candidates often confuse it with

• EC2 provides host control; Lambda runs event functions and Fargate runs containers without host management.
• EC2 instances provide compute; Auto Scaling maintains fleet count and ELB distributes traffic.

Key takeaway

Choose EC2 when control or compatibility is a hard requirement, then make instances replaceable and right-sized.

Related services

• Amazon EC2 Auto Scaling
• Elastic Load Balancing (ELB)
• Amazon EBS
• AWS Systems Manager

Relevant exam tasks

• D2.1
• D3.2
• D4.2

Learn more

• Amazon EC2