AWS Interview Questions and Answers
Core services, IAM, networking, storage and cost-aware architecture.
Whether you are preparing for entry-level AWS interview questions for freshers or senior software engineer interview questions addressing concurrency, scalability, and system architecture, this track provides peer-reviewed model answers with syntax walkthroughs, edge cases, and practical interview tips.
1 What is the difference between a security group and a network ACL? Easy
Both control traffic in a VPC, but at different layers.
- Security groups are stateful and attached to ENIs or instances. Return traffic is automatically allowed. Rules are allow-only and evaluated as a whole.
- Network ACLs are stateless and attached to subnets. You must allow both inbound and outbound traffic, including ephemeral ports. They support allow and deny rules and are evaluated in numbered order, lowest first.
aws ec2 describe-security-groups --group-ids sg-0abc123
aws ec2 describe-network-acls --filters Name=association.subnet-id,Values=subnet-123
By default, security groups deny all inbound and allow all outbound; the default NACL allows everything. A typical design uses security groups for fine-grained instance rules and NACLs as a coarse subnet-level guardrail.
2 What is the difference between EC2 instance store and EBS? Easy
Both provide block storage to EC2, but with different durability and lifecycle.
- Instance store is physically attached NVMe or SSD storage on the host. It offers very high IOPS and low latency, but data is ephemeral: it is lost on stop, terminate, or host failure. It cannot be detached or snapshotted.
- EBS is network-attached, replicated within an Availability Zone, and persists independently of the instance. Volumes can be detached, reattached, and snapshotted to S3. It supports encryption, resizing, and volume types tuned for IOPS (io2), throughput (gp3), or cold data (sc1).
Choose instance store for caches, scratch space, and temporary buffers. Choose EBS for boot volumes, databases, and anything that must survive a reboot. Many workloads combine them: instance store for a cache layer and EBS for durable data.
Frequently Asked Questions About AWS Interviews
What do hiring managers evaluate in AWS technical rounds?
Technical interviewers look for foundational fluency, idiomatic syntax, clarity when communicating complex logic, and awareness of performance trade-offs (e.g. memory footprint, render performance, and network latency) in production environments.
What are the best interview tips for practicing AWS questions?
Use active recall: summarize each answer in your own words before revealing the model solution. Focus on explaining why a certain approach is chosen rather than just memorizing code syntax.