Почему не может способные имена твердости?

Как набор других вопросов, я не могу работать apt-get update иногда. Перезапуск или ожидание некоторое время заставляют проблему уйти. У меня никогда нет проверки с помощью ping-запросов проблем или посещения соответствующих URL в браузере.

Я попробовал каждый проголосовавший ответ напрасно. Что apt выполнение, которое так отличается от ping или мой браузер? Например, когда я работаю apt-get update Я вижу это:

Err:1 https://download.docker.com/linux/ubuntu xenial InRelease
  Could not resolve host: download.docker.com
Err:2 https://deb.opera.com/opera-stable stable InRelease
  Could not resolve host: deb.opera.com
Err:3 http://ppa.launchpad.net/danielrichter2007/grub-customizer/ubuntu xenial InRelease
  Could not resolve 'ppa.launchpad.net'
Err:4 http://ppa.launchpad.net/saiarcot895/myppa/ubuntu xenial InRelease
  Could not resolve 'ppa.launchpad.net'
Err:5 http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu xenial InRelease
  Could not resolve 'ppa.launchpad.net'
Err:6 http://repository.spotify.com stable InRelease
  Could not resolve 'repository.spotify.com'
Err:7 http://dl.google.com/linux/chrome/deb stable InRelease
  Could not resolve 'dl.google.com'
Err:8 http://archive.ubuntu.com/ubuntu xenial InRelease
  Could not resolve 'archive.ubuntu.com'
Err:9 http://archive.ubuntu.com/ubuntu xenial-updates InRelease
  Could not resolve 'archive.ubuntu.com'
Err:10 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
  Could not resolve 'archive.ubuntu.com'
Err:11 http://archive.ubuntu.com/ubuntu xenial-security InRelease
  Could not resolve 'archive.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial/InRelease  Could not resolve 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-updates/InRelease  Could not resolve 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-backports/InRelease  Could not resolve 'archive.ubuntu.com'
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-security/InRelease  Could not resolve 'archive.ubuntu.com'
W: Failed to fetch https://download.docker.com/linux/ubuntu/dists/xenial/InRelease  Could not resolve host: download.docker.com
W: Failed to fetch http://ppa.launchpad.net/danielrichter2007/grub-customizer/ubuntu/dists/xenial/InRelease  Could not resolve 'ppa.launchpad.net'
W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/InRelease  Could not resolve 'dl.google.com'
W: Failed to fetch https://deb.opera.com/opera-stable/dists/stable/InRelease  Could not resolve host: deb.opera.com
W: Failed to fetch http://ppa.launchpad.net/saiarcot895/myppa/ubuntu/dists/xenial/InRelease  Could not resolve 'ppa.launchpad.net'
W: Failed to fetch http://repository.spotify.com/dists/stable/InRelease  Could not resolve 'repository.spotify.com'
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/xenial/InRelease  Could not resolve 'ppa.launchpad.net'
W: Some index files failed to download. They have been ignored, or old ones used instead.

Выполнение ping download.docker.com:

PING d2h67oheeuigaw.cloudfront.net (52.85.41.233) 56(84) bytes of data.
64 bytes from server-52-85-41-233.mel50.r.cloudfront.net (52.85.41.233): icmp_seq=1 ttl=251 time=18.8 ms
64 bytes from server-52-85-41-233.mel50.r.cloudfront.net (52.85.41.233): icmp_seq=2 ttl=251 time=18.4 ms
64 bytes from server-52-85-41-233.mel50.r.cloudfront.net (52.85.41.233): icmp_seq=3 ttl=251 time=19.5 ms

И посещение страницы в моем браузере хорошо работает. Как я могу сделать apt-get "просто работа"?

Вот содержание моего /etc/apt/resolv.conf:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.1.1
search home.gateway