Each subnet must reside entirely within one Availability Zone and cannot span zones
...
VPC: 10/16 ( R1) = sub1: 10.0.1/24 (R1/AZ1) + sub2: 10.0.2/24 (R1/AZ2) + sub3: 10.0.3/24 /24 (R1/AZ3) (R1= Region 1, AZ1= Availability Zone 1)
VPC to Customer premises:
AWS Direct Connect or
VPN connections from on-premises
connecting VPCs in different AWS Regions using either
AWS-managed networks or
non-AWS networks ( Private network/Internet-ISP = AWS Direct Connect or VPN connection )
Single Region Multi-VPC Connectivity
...
https://aws.amazon.com/answers/networking/aws-multiple-region-multi-vpc-connectivity/
VPC Peering
networking connection between two VPCs ( between your own VPCs ( same/different Region) or with a VPC in another AWS account )
