How does Lambda no-vpc mode (default Lambda mode) function access other AWS services?

Question

I know that the Lambda service uses an internal VPC for all the Lambda functions created in default mode (Lambda functions not connected to my private VPCs). This "Lambda service VPC" has access to inte.net and other AWS services.

So my question is: does it use inte.net to access to other AWS services (for example, S3) or it uses a private connection through the AWS backbone to access these other services? I would like to know if when I call AWS services from the Lambda this request goes through inte.net or does not leave AWS.network.

Answer 1

According to AWS Lambda Security Overview Whitepaper there's a passage on how requests are handled:

Traffic within the Lambda service (from the load balancer down) passes through an isolated internal virtual private cloud (VPC), owned by the Lambda service, within the AWS Region to which the request was sent.

Invocation model:

Full documentation on Lambda Invoke Modes is here .