Therefore, you might experience the following error during an apt update :
W: GPG error: http://last.public.ovh.hdaas.snap.mirrors.ovh.net/debian jessie Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY DC286CCC60B23E2F
E: The repository 'http://last.public.ovh.hdaas.snap.mirrors.ovh.net/debian jessie Release' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
To add the new key on your server, please issue this command :