daunderground@ubuntu:~$ grep 'archive.*main' /etc/apt/sources.list
deb http://us.archive.ubuntu.com/ubuntu/ precise main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ precise main restricted
deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted
deb http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse