summary-plus.md

# ENI

An elastic network interface is a logical networking component in a VPC that represents a virtual network card.

It can include the following attributes:

A primary private IPv4 address from the IPv4 address range of your VPC

- One or more secondary private IPv4 addresses from the IPv4 address range of your VPC
- One Elastic IP address (IPv4) per private IPv4 address
- One public IPv4 address
- One or more IPv6 addresses
- One or more security groups

Each instance has a default network interface, called the primary network interface. You cannot detach a primary network interface from an instance. You can create and attach additional network interfaces. The maximum number of network interfaces that you can use varies by instance type.

- In a VPC, all subnets have a modifiable attribute that determines whether network interfaces created in that subnet (and therefore instances launched into that subnet) are assigned a public IPv4 address. The public IPv4 address is assigned from Amazon's pool of public IPv4 addresses. When you launch an instance, the IP address is assigned to the primary network interface that's created.

# VPC Peering

Instances in either VPC can communicate with each other as if they are within the same network. The VPCs can be in different regions (also known as an inter-region VPC peering connection). This is neither a gateway nor a VPN connection, and does not rely on a separate piece of physical hardware.

A VPC peering connection helps you to facilitate the transfer of data. For example, if you have more than one AWS account, you can peer the VPCs across those accounts to create a file sharing network. You can also use a VPC peering connection to allow other VPCs to access resources you have in one of your VPCs.

- In case of cross account peering connection, one account creates the peering connection request and other approves the same

Instances in either VPC can communicate with each other as if they are within the same network. The VPCs can be in different regions (also known as an inter-region VPC peering connection). This is neither a gateway nor a VPN connection, and does not rely on a separate piece of physical hardware.

A VPC peering connection helps you to facilitate the transfer of data. For example, if you have more than one AWS account, you can peer the VPCs across those accounts to create a file sharing network. You can also use a VPC peering connection to allow other VPCs to access resources you have in one of your VPCs.

- In case of cross account peering connection, one account creates the peering connection request and other approves the same

# AWS Direct Connect

Direct Connect provides Amazon Web Services (AWS) customers with a way to transfer data that does not involve using the public Internet.

Say your company uses multiple Amazon VPCs and is setting up a new office.

- Establish a private connection from your new office’s network to your Amazon VPC using AWS Direct Connect
- This option provides predictable network performance, reduces bandwidth costs, and doesn’t require that customers be responsible for implementing high availability solutions for all VPN endpoints.
- The downside of this option (possible requiring additional telecom and hosting provider relationships) is mitigated in this instance because the office is new and would need to provision a whole new network anyway.

AWS Direct Connect uses dedicated, private network connections between your intranet and Amazon VPC. Use AWS Direct connect:

- If you have an immediate need, have low to modest bandwidth requirements, and can tolerate the inherent variability in Internet-based connectivity.
- A VPC VPN Connection utilizes IPSec to establish encrypted network connectivity between your intranet and Amazon VPC over the Internet.

You are uploading large amounts of data overnight, 3 to 5 TB to an S3 bucket. What steps can you take to decrease the amount of time to perform these uploads?

Using AWS Direct Connect, data that would have previously been transported over the Internet can now be delivered through a private network connection between AWS and your datacenter or corporate network. In many circumstances, private network connections can reduce costs, increase bandwidth, and provide a more consistent network experience than Internet-based connections.

# Cloudformation