NAT Gateway for private subnet internet in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a NAT Gateway in AWS?

A NAT Gateway is a service that allows instances in a private subnet to access the internet or other AWS services, while preventing inbound internet traffic to those instances.

beginner

Why do private subnets need a NAT Gateway to access the internet?

Private subnets do not have direct internet access. A NAT Gateway enables outbound internet traffic from private subnets by routing requests through it, while keeping the subnet secure from inbound internet traffic.

intermediate

Where should you place a NAT Gateway in your AWS VPC?

You should place the NAT Gateway in a public subnet with a route to an Internet Gateway. This allows it to forward traffic from private subnets to the internet.

intermediate

How do you configure route tables for private subnets to use a NAT Gateway?

In the private subnet's route table, add a default route (0.0.0.0/0) that points to the NAT Gateway's ID. This directs outbound internet traffic through the NAT Gateway.

advanced

What is the difference between a NAT Gateway and a NAT Instance?

A NAT Gateway is a managed AWS service that is highly available and scales automatically. A NAT Instance is a user-managed EC2 instance that requires manual scaling and maintenance.

Where should a NAT Gateway be placed in an AWS VPC?

A In a private subnet

B In a VPN Gateway

C In the Internet Gateway

D In a public subnet

A NAT Gateway must be placed in a public subnet to route traffic from private subnets to the internet.

What does a NAT Gateway allow instances in a private subnet to do?

A Access the internet for outbound traffic

B Directly connect to other VPCs

C Receive inbound internet traffic

D Host public websites

A NAT Gateway allows instances in private subnets to initiate outbound internet connections while blocking inbound traffic.

Which route should be added to a private subnet's route table to use a NAT Gateway?

A 0.0.0.0/0 to NAT Gateway

B Specific IP range to NAT Gateway

C Local route only

D 0.0.0.0/0 to Internet Gateway

Private subnets route all internet-bound traffic (0.0.0.0/0) to the NAT Gateway.

What is a key advantage of using a NAT Gateway over a NAT Instance?

A Runs on EC2 instances

B Requires manual scaling

C Is managed and scales automatically

D Allows inbound internet traffic

NAT Gateways are managed by AWS and scale automatically, unlike NAT Instances.

Can a NAT Gateway be used to allow inbound internet traffic to private subnet instances?

A Yes, it allows inbound traffic

B No, it only allows outbound traffic

C Only if configured with security groups

D Only for HTTPS traffic

NAT Gateways do not allow inbound internet traffic to private subnet instances; they only enable outbound connections.

Explain how a NAT Gateway enables internet access for instances in a private subnet.

Think about where the NAT Gateway lives and how routes direct traffic.

Describe the differences between a NAT Gateway and a NAT Instance in AWS.

Consider ease of use and reliability.