Core Concepts for Amazon Virtual Private Cloud (VPC)

Posted on:November 22, 2023 at 12:00 AM

Here are the key insights about VPC in AWS in a Q&A format:

What is a VPC in AWS?

A Virtual Private Cloud (VPC) is a virtual network dedicated to an AWS account. It allows launching AWS resources in a private virtual network.

What are the key components of a VPC?

Can a VPC span multiple regions?

No, a VPC is limited to a single region. To connect VPCs across regions, you need to use VPC peering.

What is a public subnet?

A subnet associated with a route table that directs internet traffic to an internet gateway is called a public subnet. Resources here get public IP addresses.

What is a private subnet?

A private subnet uses a NAT gateway to allow outbound internet access but does not assign public IPs to resources. Inbound internet access is not allowed.

How can resources in a private subnet access the internet?

Resources in a private subnet can access the internet by using a NAT Gateway. The route table directs internet traffic to the NAT gateway.

How can you connect a VPC to other AWS services?

You can create an VPC Endpoint to privately connect your VPC to supported AWS services like S3, SNS etc. Traffic stays within the AWS network.

What is a security group in AWS?

A security group acts as a virtual firewall to control inbound and outbound traffic for resources. It has rules to allow/deny traffic.

How can you test connectivity in a VPC?

Use the VPC Reachability Analyzer to test connectivity between resources and troubleshoot issues.

ref:

internet_gateway 
internet_gateway <---> public_subnet

Nat gateway:

```mermaid
flowchart LR
	internet <---> nat_gateway
	nat_gateway <---> private_subnet

routing table: routing table is attached to subnet ![[Pasted image 20210702170207.png]]

aws regions:

In AWS a region is a separate geographical area where you might want to deploy your service. ==A region is split up into separate isolated physical datacentres called availability zones. Each region has at least two availability zones.==

vpc peering tutorial

vpc reachability analyzer

![[Pasted image 20210705141045.png]]

by creating an endpoint

Create Endpoint | VPC Management Console

![[Pasted image 20210630171546.png]]

A security group acts as a virtual firewall for your instance to control inbound and outbound traffic.

Basically firewall?

VPC tied everything together

![[Pasted image 20210630172047.png]]

This is the networking part, think virtual routers

What is Amazon VPC? - Amazon Virtual Private Cloud

The following are the key concepts for VPCs: Virtual private cloud (VPC) — A virtual network dedicated to your AWS account. Subnet — A range of IP addresses in your VPC. Route table — A set of rules, called routes, that are used to determine where network traffic is directed. Internet gateway — A gateway that you attach to your VPC to enable communication between resources in your VPC and the internet. VPC endpoint — Enables you to privately connect your VPC to supported AWS services and VPC endpoint services powered by PrivateLink without requiring an internet gateway, NAT device, VPN connection, or AWS Direct Connect connection. Instances in your VPC do not require public IP addresses to communicate with resources in the service. Traffic between your VPC and the other service does not leave the Amazon network. For more information, see AWS PrivateLink and VPC endpoints. CIDR block —Classless Inter-Domain Routing. An internet protocol address allocation and route aggregation methodology. For more information, see Classless Inter-Domain Routing in Wikipedia.

no

A gateway route table supports routes where the target is local (the default local route) ![[Pasted image 20210630174043.png]]

ref:VPC with a single public subnet - Amazon Virtual Private Cloud

![[Pasted image 20210630174221.png]]

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