How many internet gateways can be attached to a custom VPC?

A custom Virtual Private Cloud (VPC) in AWS can have only one Internet Gateway attached to it at any given time. This limitation is in place because the Internet Gateway serves as a target for route table entries for internet-routable traffic and as a means to enable communication between instances in the VPC and the internet.

When an Internet Gateway is attached to a VPC, it allows instances in that VPC to communicate with internet resources. This is critical for applications that require direct communication over the internet. If you need connectivity for multiple VPCs, you would need to set up separate Internet Gateways for each respective VPC, as each VPC can have only one Internet Gateway to facilitate its internet connection.

In contrast, if the number of Internet Gateways were higher than one, it could complicate routing decisions and the management of internet traffic, undermining the simplicity and effectiveness of the VPC architecture.