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 - How many usable IP addresses does a /24 subnet in an AWS VPC have?
A /24 has 256 addresses, but AWS reserves five in every subnet, so 251 are usable. The reserved ones are the network address, VPC router, DNS, one for future use, and the broadcast address.
BeginnerQuick answer1 min read