Por que não pode resolver nomes?

Question

Como um monte de outras perguntas , não consigo executar apt-get update às vezes . Reiniciar ou esperar por um tempo faz o problema desaparecer. Eu nunca tenho problemas ao fazer ping ou visitar as respectivas URLs em um navegador.

Eu tentei todas as respostas aprovadas sem sucesso. O que é apt fazendo isso é tão diferente de ping ou meu navegador? Por exemplo, quando eu executo apt-get update , vejo isso:

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.

Executando 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

E visitar a página no meu navegador funciona bem. Como posso fazer com que apt-get "apenas funcione"?

Aqui está o conteúdo do meu /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

    

Answer 1

Execute este comando no terminal e você poderá usar apt e apt-get normalmente no futuro:)

echo 'Acquire::ForceIPv4 "true";' | sudo tee /etc/apt/apt.conf.d/99force-ipv4

    

Answer 2

Se /etc/atp/apt.conf existir, faça uma cópia do arquivo e edite o original para comentar a seguinte linha:

Acquire::http::Proxy "http://proxyaddress:proxyport";