I can’t do apt-get update

sudo apt-get update
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Hit:2 http://repo.percona.com/apt xenial InRelease
Hit:3 https://repos.sonar.digitalocean.com/apt main InRelease
Err:4 http://ams2.clouds.archive.ubuntu.com/ubuntu xenial InRelease
  Temporary failure resolving 'ams2.clouds.archive.ubuntu.com'
Err:5 http://ams2.clouds.archive.ubuntu.com/ubuntu xenial-updates InRelease
  Temporary failure resolving 'ams2.clouds.archive.ubuntu.com'
Err:6 http://ams2.clouds.archive.ubuntu.com/ubuntu xenial-backports InRelease
  Temporary failure resolving 'ams2.clouds.archive.ubuntu.com'

I can’t ping ams2.clouds.archive.ubuntu.com. It’s working host?

ping ams2.clouds.archive.ubuntu.com
ping: unknown host ams2.clouds.archive.ubuntu.com

But network works fine

ping google.com
PING google.com (172.217.10.110) 56(84) bytes of data.

cat /etc/*-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"
NAME="Ubuntu"
VERSION="16.04.1 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.1 LTS"
VERSION_ID="16.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
VERSION_CODENAME=xenial
UBUNTU_CODENAME=xenial

This is my /etc/apt/sources.list

## Note, this file is written by cloud-init on first boot of an instance
## modifications made here will not survive a re-bundle.
## if you wish to make changes you can:
## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
##     or do the same in user-data
## b.) add sources in /etc/apt/sources.list.d
## c.) make changes to template file /etc/cloud/templates/sources.list.tmpl

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial main restricted
deb-src http://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial-updates main restricted
deb-src http://ams2.clouds.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://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial universe
deb-src http://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial universe
deb http://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial-updates universe
deb-src http://ams2.clouds.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://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial multiverse
deb-src http://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial multiverse
deb http://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial-updates multiverse
deb-src http://ams2.clouds.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://ams2.clouds.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://ams2.clouds.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 xenial partner
# deb-src http://archive.canonical.com/ubuntu xenial partner

How can I fix it?