Docker uses a special ("default") value for --net if no network is specified.

The "default" value is set as default value in this flag;
https://github.com/docker/docker/blob/73a5393bf3530815a608725fe2546121ccadbfe4/runconfig/opts/parse.go#L83

And was introduced here;
da5a3e6

This value was needed because Windows does not have a "bridge" network, so requires some special handling to check if the default (type of) network is used, for example, in hostconfig_windows.go

• Should we use a literal "default" string for the default value? Can we use (e.g.) null (no value) as the default?
• In the current situation the --net flag shows "default" as it's default value, but (on Linux), the default is actually "bridge", so this is confusing

Just opening this for discussion, not a high-priority case.