Não foi possível resolver 'proxyaddress'

Question

Eu sei que há toneladas de perguntas semelhantes, mas não consegui encontrar uma solução para todas elas. No meu caso, não tenho ideia do que proxyaddress significa.

apt-get update:

Err:1 http://linux.dropbox.com/ubuntu wily InRelease
  Could not resolve 'proxyaddress'
Err:2 http://repository.spotify.com stable InRelease                                     
  Could not resolve 'proxyaddress'
Err:3 http://dl.google.com/linux/chrome/deb stable InRelease                             
  Could not resolve 'proxyaddress'
Err:4 http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu xenial InRelease
  Could not resolve 'proxyaddress'
Reading package lists... Done  
W: Failed to fetch http://linux.dropbox.com/ubuntu/dists/wily/InRelease  Could not resolve 'proxyaddress'
W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/InRelease  Could not resolve 'proxyaddress'
W: Failed to fetch http://repository.spotify.com/dists/stable/InRelease  Could not resolve 'proxyaddress'
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/xenial/InRelease  Could not resolve 'proxyaddress'
W: Some index files failed to download. They have been ignored, or old ones used instead.

/etc/apt/apt.conf:

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

/etc/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 8.8.8.8 # tried but did not work.
# nameserver 8.8.4.4
nameserver 127.0.1.1

nslookup > servidor:

Default server: 127.0.1.1
Address: 127.0.1.1#53

netstat -nap:

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 127.0.1.1:53            0.0.0.0:*               LISTEN      945/dnsmasq