$ docker pull hello-world
Using default tag: latest
error during connect: Post https://192.168.99.100:2376/v1.40/images/create?fromImage=hello-world&tag=latest: dial tcp 192.168.99.100:2376: connectex: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
解决方法：
cd Docker Toolbox
运行start.sh
注：
可能需要多试几次
成功：