Interview Q&A / AWS & Cloud

1. What are EC2 placement groups and what are the three strategies?

   A placement group controls how instances sit on physical hardware. Cluster packs them close for low latency, spread puts each on separate hardware to limit correlated failure, and partition groups them in racks that do not share hardware.

   IntermediateQuick answer1 min read
2. What is EC2 instance store and how is it different from EBS?

   Instance store is disk physically attached to the host computer, giving very fast but temporary storage. Its data is lost when the instance stops, terminates or the hardware fails. EBS is network-attached and persists independently of the instance.

   IntermediateQuick answer1 min read
3. What is EC2 user data and how is it different from instance metadata?

   User data is a script or text you give an instance at launch, typically run once to install software. Instance metadata is information about the running instance, such as its ID, IP and IAM role credentials, which the instance reads from a local endpoint.

   IntermediateQuick answer1 min read
4. What is the difference between target tracking, step and scheduled scaling in an Auto Scaling group?

   Target tracking holds a metric near a value you set, like 50% CPU. Step scaling adds or removes capacity in sized steps based on alarm thresholds. Scheduled scaling changes capacity at set times for predictable load.

   IntermediateQuick answer1 min read