Interview Q&A / AWS & Cloud
AWS & Cloud interview questions
EC2, S3, Lambda, IAM and VPC basics, with when to pick which service.
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- What is a VPC, and what is the difference between public and private subnets?
A VPC is your own private network inside AWS. A public subnet has a route to an internet gateway, so resources with public IPs can be reached from the internet. A private subnet has no such route; its servers reach the internet only outbound, through a NAT gateway placed in a public subnet.
IntermediateIn-depth4 min read - What is the difference between a security group and a network ACL in AWS?
A security group is a stateful firewall attached to an instance's network interface, with allow rules only. A network ACL is a stateless firewall on a subnet, with numbered allow and deny rules checked in order. Because NACLs are stateless, you must allow return traffic explicitly, usually on ephemeral ports.
IntermediateIn-depth4 min read - What is the difference between VPC peering and AWS Transit Gateway?
VPC peering is a one-to-one private link between two VPCs and it is not transitive. Transit Gateway is a central hub that connects many VPCs and on-premises networks, so each network connects once.
IntermediateQuick answer1 min read