AWS ubuntu unable to resolve host

Describes the cause and action for error messages.

Error Message(English)：
ubuntu unable to resolve host

Resolution

14.04 - ubuntu unable to resolve host
https://askubuntu.com/questions/1074275/ubuntu-unable-to-resolve-host

Unable to resolve host in Ubuntu using sudo
https://askubuntu.com/questions/895654/unable-to-resolve-host-in-ubuntu-using-sudo

sudo - Unable to resolve host
https://askubuntu.com/questions/790233/unable-to-resolve-host-name

hostname - Lost access to sudo
https://askubuntu.com/questions/368902/lost-access-to-sudo

Unable to resolve host in Ubuntu using sudo - Ask Ubuntu
https://askubuntu.com/a/895720

Keep getting "sudo: unable to resolve host" - Ask Ubuntu
https://askubuntu.com/questions/276629/keep-getting-sudo-unable-to-resolve-host?noredirect=1&lq=1

Solve sudo sending useless emails “problem with defaults entries ...
https://bgstack15.wordpress.com/2016/06/06/solve-sudo-sending-useless-emails-problem-with-defaults-e・・・

mitchellh/vagrant-aws - GitHub
https://github.com/mitchellh/vagrant-aws/issues/495

Clean Blog - Sample Post
https://fullstackforger.com/