apt-get update无法正常工作，我无法添加任何存储库

伙计们请帮助Sudo apt-get update无效，我无法添加任何存储库，谢谢。

hashik@Hashik:~$ sudo apt-get update [sudo] password for hashik: Err:1 http://in.archive.ubuntu.com/ubuntu yakkety InRelease Could not resolve 'in.archive.ubuntu.com' Err:2 http://security.ubuntu.com/ubuntu yakkety-security InRelease Could not resolve 'security.ubuntu.com' Err:3 http://ppa.launchpad.net/noobslab/apps/ubuntu yakkety InRelease Could not resolve 'ppa.launchpad.net' Err:4 http://in.archive.ubuntu.com/ubuntu yakkety-updates InRelease Could not resolve 'in.archive.ub hashik@Hashik:~$ sudo apt-get update [sudo] password for hashik: Err:1 http://in.archive.ubuntu.com/ubuntu yakkety InRelease Could not resolve 'in.archive.ubuntu.com' Err:2 http://security.ubuntu.com/ubuntu yakkety-security InRelease Could not resolve 'security.ubuntu.com' Err:3 http://ppa.launchpad.net/noobslab/apps/ubuntu yakkety InRelease Could not resolve 'ppa.launchpad.net' Err:4 http://in.archive.ubuntu.com/ubuntu yakkety-updates InRelease Could not resolve 'in.archive.ubuntu.com' Err:5 http://in.archive.ubuntu.com/ubuntu yakkety-backports InRelease Could not resolve 'in.archive.ubuntu.com' Reading package lists... Done W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/yakkety/InRelease Could not resolve 'in.archive.ubuntu.com' W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/yakkety-updates/InRelease Could not resolve 'in.archive.ubuntu.com' W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/yakkety-backports/InRelease Could not resolve 'in.archive.ubuntu.com' W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/yakkety-security/InRelease Could not resolve 'security.ubuntu.com' W: Failed to fetch http://ppa.launchpad.net/noobslab/apps/ubuntu/dists/yakkety/InRelease Could not resolve 'ppa.launchpad.net' W: Some index files failed to download. They have been ignored, or old ones used instead.untu.com' Err:5 http://in.archive.ubuntu.com/ubuntu yakkety-backports InRelease Could not resolve 'in.archive.ubuntu.com' Reading package lists... Done W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/yakkety/InRelease Could not resolve 'in.archive.ubuntu.com' W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/yakkety-updates/InRelease Could not resolve 'in.archive.ubuntu.com' W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/yakkety-backports/InRelease Could not resolve 'in.archive.ubuntu.com' W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/yakkety-security/InRelease Could not resolve 'security.ubuntu.com' W: Failed to fetch http://ppa.launchpad.net/noobslab/apps/ubuntu/dists/yakkety/InRelease Could not resolve 'ppa.launchpad.net' W: Some index files failed to download. They have been ignored, or old ones used instead.