I am getting this error while installing docker CE on my ubuntu machine
curl: (6) Could not resolve host: download.docker.com
gpg: no valid OpenPGP data found.
While performing the step
Add Docker’s official GPG key:
$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
as mentioned here https://docs.docker.com/engine/installation/linux/docker-ce/ubuntu/#install-docker-ce-1