apt-get update
Err http://security.debian.org jessie/updates InRelease
Err http://ftp.debian.org jessie-updates InRelease
Err http://security.debian.org jessie/updates Release.gpg
Could not resolve 'security.debian.org'
Err http://ftp.debian.org jessie-updates Release.gpg
Could not resolve 'ftp.debian.org'
Err http://ftp.us.debian.org testing InRelease
Err http://ftp.us.debian.org testing Release.gpg
Could not resolve 'ftp.us.debian.org'
Reading package lists... Done
W: Failed to fetch http://ftp.us.debian.org/debian/dists/testing/InRelease
W: Failed to fetch http://ftp.debian.org/debian/dists/jessie-updates/InRelease
W: Failed to fetch http://security.debian.org/dists/jessie/updates/InRelease
W: Failed to fetch http://security.debian.org/dists/jessie/updates/Release.gpg Could not resolve 'security.debian.org'
W: Failed to fetch http://ftp.debian.org/debian/dists/jessie-updates/Release.gpg Could not resolve 'ftp.debian.org'
W: Failed to fetch http://ftp.us.debian.org/debian/dists/testing/Release.gpg Co uld not resolve 'ftp.us.debian.org'
W: Some index files failed to download. They have been ignored, or old ones used instead.