Why is the SDK try to connect to both IPv4 and IPv6 addresses of iotcore endpoint simultaneously ?

[kiranpradeep]

I am using aws-iot-device-sdk-v2 with Node.js. I was inspecting logs obtained after enabling // io.enable_logging(io.LogLevel.DEBUG); //. I see that SDK after resolving host to IPs, is trying to connect to both IPv4 and IPv6 addresses simultaneously. This is surprising. Most software does not do this.

1. Is this behavior that can be controlled? E.g. If I prefer the SDK to connect to a single IP and return with failure if connect fails.
2. I also like to understand, what is the scenario that benefits from this kind of behavior.

I have attached logs.txt

[bretambrose]

This is intentional. The short answer is a strong push for happy eyeballs support: https://datatracker.ietf.org/doc/html/rfc6555

There is no way to disable this behavior.