Internet Gateway

5 minutes 5 Questions

An Internet Gateway (IGW) is a horizontally scalable, redundant, and highly available VPC component that allows communication between instances in your VPC and the internet. It serves two purposes: to provide a target in your VPC route tables for internet-routable traffic and to perform network address translation (NAT) for instances that have been assigned public IPv4 addresses.

Guide: Understanding and Answering Questions on Amazon VPC's Internet Gateway

An Internet Gateway is a crucial component in the Amazon VPC (Virtual Private Cloud), enabling communication between instances in your VPC and the Internet.

Its primary importance lies in its ability to allow outbound and inbound traffic from your VPC directly to the Internet and vice-versa. Internet Gateway presents a high bandwidth, highly available link between your resources and the outer network.

The way it works is quite straightforward. It routes traffic entering with a destination of the Internet (0.0.0.0/0 in CIDR notation) to the Internet, and routes traffic coming from the Internet, targeting instances in the VPC, through its NAT (Network Address Translation) capability. Remember, for an instance to be able to communicate with the Internet, it not only needs an Internet Gateway, but also requires a correctly configured routing table and security group rules.

Exam Tips: Answering Questions on Internet Gateway

1. Understand the basics: Ensure you are firm with basic concepts like its purpose, how it works, and how it is different from NAT Gateways and Virtual Private Gateways.

2. Consider its functionalities: Know that it enables instances in your VPC to connect to the Internet, cannot be detached from a VPC until all dependencies are deleted, and enables a new VPC to default to true.

3. Draw a mental diagram: Imagining the architecture of how different gateways interact may aid in solving complex scenarios.

4. Practice questions: This helps familiarize with the type of questions that may appear in the exam.

Comprehending these concepts will equip you with the knowledge necessary to answer any potential exam questions regarding Internet Gateway.

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Question 1

A company has deployed a web application in their VPC's public subnet which can be accessed over the internet. However, users are unable to access the application. What should be the first step in troubleshooting?

Check if the VPC peering connection is established Check if the Internet Gateway is attached to the VPC Check if a NAT gateway is attached to the VPC Check if the application's security group allows only VPC traffic

Correct Answer: Check if the Internet Gateway is attached to the VPC

The first step in troubleshooting should be to verify if the Internet Gateway is attached to the VPC. An Internet Gateway is required for instances in a public subnet to have internet access.

Question 2

You are tasked to create a VPC with no internet access at all. What should you do?

Create a VPC and attach a NAT Gateway only Create a VPC and disable default VPC routing Create a VPC with an Internet Gateway but deny all traffic Create a VPC without attaching an Internet Gateway

Correct Answer: Create a VPC without attaching an Internet Gateway

To create a VPC without internet access, you should create a VPC without attaching an Internet Gateway. Internet Gateway is required for instances to have internet access.

Question 3

You have created a VPC with an attached Internet Gateway, and you deployed two subnets, one public and one private. However, EC2 instances within a private subnet cannot access the internet. What is the cause?

Private subnet instances need NAT Gateway for internet access Instances in a private subnet are incorrectly launched Private subnet instances should be moved to the public subnet You need to add more routes to the route table

Correct Answer: Private subnet instances need NAT Gateway for internet access

Private subnet instances cannot access the Internet directly through the Internet Gateway. You need a NAT Gateway in the public subnet to enable internet access for instances in the private subnet.

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