AWS Transit Gateway is a network transit hub that you can use to interconnect your VPCs and on-premises networks through a central gateway. AWS Transit Gateway simplifies and scales the connectivity between your on-premises networks and AWS, as you only need to create and manage a single connection from the central gateway to each on-premises network, rather than individual connections to each VPC. You can also use AWS Transit Gateway to connect to other AWS services, such as Amazon S3, Amazon DynamoDB, and AWS PrivateLink12. AWS Transit Gateway supports thousands of VPCs per gateway, and enables you to peer Transit Gateways across AWS Regions3.

The other options are not AWS services or features that can simplify and scale the connectivity between on-premises networks and hundreds of VPCs using AWS Direct Connect. VPC endpoints enable private connectivity between your VPCs and supported AWS services, but do not support on-premises networks4. Amazon Route 53 is a DNS service that helps you route internet traffic to your resources, but does not provide network connectivity5. AWS Secrets Manager is a service that helps you securely store and manage secrets, such as database credentials and API keys, but does not relate to network connectivity