当我运行时，出现这个错误apt-get update。
root@server1:~# sudo apt-get update
Err:1 http://apt.izzysoft.de/ubuntu generic InRelease
Temporary failure resolving 'apt.izzysoft.de'
Err:2 http://ppa.launchpad.net/ondrej/apache2/ubuntu xenial InRelease
Temporary failure resolving 'ppa.launchpad.net'
Err:3 http://apt.newrelic.com/debian newrelic InRelease
Temporary failure resolving 'apt.newrelic.com'
Err:4 http://software.virtualmin.com/gpl/ubuntu virtualmin-xenial InRelease
Temporary failure resolving 'software.virtualmin.com'
Err:5 http://ppa.launchpad.net/ondrej/php/ubuntu xenial InRelease
Temporary failure resolving 'ppa.launchpad.net'
Err:6 http://security.ubuntu.com/ubuntu xenial-security InRelease
Temporary failure resolving 'security.ubuntu.com'
Err:7 http://software.virtualmin.com/gpl/ubuntu virtualmin-universal InRelease
Temporary failure resolving 'software.virtualmin.com'
Err:8 http://archive.ubuntu.com/ubuntu xenial InRelease
Temporary failure resolving 'archive.ubuntu.com'
Err:9 https://deb.nodesource.com/node_4.x xenial InRelease
Could not resolve host: deb.nodesource.com
Err:10 http://archive.ubuntu.com/ubuntu xenial-updates InRelease
Temporary failure resolving 'archive.ubuntu.com'
Err:11 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
Temporary failure resolving 'archive.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial/InRelease Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-updates/InRelease Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-backports/InRelease Temporary failure resolving 'archive.ubuntu.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/xenial-security/InRelease Temporary failure resolving 'security.ubuntu.com'
W: Failed to fetch http://software.virtualmin.com/gpl/ubuntu/dists/virtualmin-xenial/InRelease Temporary failure resolving 'software.virtualmin.com'
W: Failed to fetch http://software.virtualmin.com/gpl/ubuntu/dists/virtualmin-universal/InRelease Temporary failure resolving 'software.virtualmin.com'
W: Failed to fetch http://apt.izzysoft.de/ubuntu/dists/generic/InRelease Temporary failure resolving 'apt.izzysoft.de'
W: Failed to fetch http://apt.newrelic.com/debian/dists/newrelic/InRelease Temporary failure resolving 'apt.newrelic.com'
W: Failed to fetch https://deb.nodesource.com/node_4.x/dists/xenial/InRelease Could not resolve host: deb.nodesource.com
W: Failed to fetch http://ppa.launchpad.net/ondrej/apache2/ubuntu/dists/xenial/InRelease Temporary failure resolving 'ppa.launchpad.net'
W: Failed to fetch http://ppa.launchpad.net/ondrej/php/ubuntu/dists/xenial/InRelease Temporary failure resolving 'ppa.launchpad.net'
W: Some index files failed to download. They have been ignored, or old ones used instead.
关于如何修复此问题，有什么建议吗？
这是我的/etc/apt/sources.list：
# deb cdrom:[Ubuntu-Server 14.04 LTS _Trusty Tahr_ - Release amd64 (20140416.2)]/ trusty main restricted
# deb cdrom:[Ubuntu-Server 14.04 LTS _Trusty Tahr_ - Release amd64 (20140416.2)]/ trusty main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu/ xenial main restricted
deb-src http://archive.ubuntu.com/ubuntu/ xenial main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu/ xenial-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu/ xenial-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu/ xenial universe
deb-src http://archive.ubuntu.com/ubuntu/ xenial universe
deb http://archive.ubuntu.com/ubuntu/ xenial-updates universe
deb-src http://archive.ubuntu.com/ubuntu/ xenial-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://archive.ubuntu.com/ubuntu/ xenial multiverse
deb-src http://archive.ubuntu.com/ubuntu/ xenial multiverse
deb http://archive.ubuntu.com/ubuntu/ xenial-updates multiverse
deb-src http://archive.ubuntu.com/ubuntu/ xenial-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu xenial-security main restricted
deb-src http://security.ubuntu.com/ubuntu xenial-security main restricted
deb http://security.ubuntu.com/ubuntu xenial-security universe
deb-src http://security.ubuntu.com/ubuntu xenial-security universe
deb http://security.ubuntu.com/ubuntu xenial-security multiverse
deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty partner
## Uncomment the following two lines to add software from Ubuntu's
## 'extras' repository.
答案1
您的/etc/apt/sources.list或目录中的文件/etc/apt/sources.list.d/混乱了。使用终端、sudo 和您最喜欢的编辑器修复它。
例子：
sudo vi /etc/apt/sources.list