VPC Flashcards
<p>What is the definition of a VPC?</p>
<p>Virtual Private Cloud - amazon lets you provision a logically isolated section of the AWS Cloud where you can launch AWS resources in a virtual network that you define. you have complete control over this network, including selection of IP address range, subnets and network gateways</p>
<p>True or false: You can only have one internet gateway per VPC</p>
<p>True</p>
<p>What are differences between the default VPC and a custom VPC?</p>
<p>Default VPCs are user-friendly, so you can imediately start deploying resources
All subnets in a default VPC have a route out to the internet
In a default VPC, each EC2 instance has both a public and private IP address</p>
<p>What is VPC peering?</p>
<p>It allows you to connect a VPC to another VPC using private IP addresses. </p>
<p>Can you use VPC peering across accounts?</p>
<p>Yes</p>
<p>What is transitive peering?</p>
<p>There is one central VPC, and individual VPCs are peered directly with it. Transitive peering allows the second VPC to then be peered with a third, allowing the first and third VPCs to share resources. This is not permitted in AWS.</p>
<p>What is a CIDR block?</p>
<p>It is a range of IP addresses available for a subnet in a VPC</p>
<p>What is default vs dedicated tenancy?</p>
<p>Default tenancy means your VPC will share hardware with other VPCs. Dedicated tenancy mans your VPC will exist on dedicated hardware. Dedicated tenancy is much more expensive than default tenancy.</p>
<p>When you create a new VPC, what else is created by default?</p>
<p>A default route table
A default network access control list
A default security group
No subnets are created</p>
<p>How many IP addresses does amazon reserve when you create a subnet?</p>
<p>5. So a /24 subnet which has 256 available addresses will only give you 251</p>
<p>Can you associate a subnet with more than one route table?</p>
<p>No. A subnet can only be associated with a single route table at a time</p>
<p>Can you associate a route table with more than one subnet?</p>
<p>Yes. Route tables can be associated with multiple subnets</p>
What does an internet gateway do?
- It provides an endpoint for internet/bound traffic that route tables can point to
- Performs network address translation (NAT), between a public IP address and the private IP address of the instance
A subnet which is associated with a route table containing a route to an internet gateway is known as what?
Public subnet
Does the default VPC automatically include a route to the internet gateway for IPv6 traffic?
No
When creating a subnet, does AWS automatically include a route to the internet from the main route table for the VPC?
No, you must add that yourself
True or false: When a new subnet is created, it is automatically associated with the main route table
True. which is why the main route table should not offer internet access
Are public IP addresses automatically assigned to instances launched within subnets in VPCs you create?
Not by default, but you can change the Auto-assign IP setting to Yes for the subnet. In the default VPC, they are automatically assigned.
True or false: A security group is limited to a single VPC
True
What is ICMP?
Internet control Message Protocol, which allows messaging between devices in an IP network
True or false: to make a subnet public, you must associate it with an internet gateway
False. Route tables point to internet gateways, and subnets are associated with route tables.
How can you make a private subnet public?
The subnet is private because it is associated with a route table that does not have a route to the internet gateway. To make the subnet public, associate it with a route table that does have a route to the internet gateway
What is Network Address Translation?
NAT acts as a bridge between private subnets and the internet, so that they can get to the internet without allowing public access
What is a NAT Instance?
An EC2 instance that acts as a gateway to the internet for a private subnet
