ubuntu@ubuntu:~$ sudo apt-get update
Ign cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423) precise InRelease
Ign cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423) precise/main TranslationIndex
Ign cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423) precise/restricted TranslationIndex
Ign cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423) precise/main Translation-en_US
Ign cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423) precise/main Translation-en
Ign cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423) precise/restricted Translation-en_US
Ign cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423) precise/restricted Translation-en
Ign
http://archive.ubuntu.com precise InRelease
Ign
http://archive.ubuntu.com precise-updates InRelease
Ign
http://security.ubuntu.com precise-security InRelease
Get:1
http://archive.ubuntu.com precise Release.gpg [198 B]
Get:2
http://security.ubuntu.com precise-security Release.gpg [198 B]
Get:3
http://archive.ubuntu.com precise-updates Release.gpg [198 B]
Get:4
http://security.ubuntu.com precise-security Release [49.6 kB]
Get:5
http://archive.ubuntu.com precise Release [49.6 kB]
Get:6
http://archive.ubuntu.com precise-updates Release [49.6 kB]
Get:7
http://security.ubuntu.com precise-security/main i386 Packages [32.9 kB]
Get:8
http://archive.ubuntu.com precise/main i386 Packages [1,274 kB]
Get:9
http://security.ubuntu.com precise-security/restricted i386 Packages [14 B]
Get:10
http://security.ubuntu.com precise-security/main TranslationIndex [73 B]
Get:11
http://security.ubuntu.com precise-security/restricted TranslationIndex [70 B]
Get:12
http://security.ubuntu.com precise-security/main Translation-en [13.6 kB]
Hit
http://security.ubuntu.com precise-security/restricted Translation-en
Get:13
http://archive.ubuntu.com precise/restricted i386 Packages [8,431 B]
Get:14
http://archive.ubuntu.com precise/main TranslationIndex [3,706 B]
Get:15
http://archive.ubuntu.com precise/restricted TranslationIndex [2,596 B]
Get:16
http://archive.ubuntu.com precise-updates/main i386 Packages [96.5 kB]
Get:17
http://archive.ubuntu.com precise-updates/restricted i386 Packages [770 B]
Get:18
http://archive.ubuntu.com precise-updates/main TranslationIndex [73 B]
Get:19
http://archive.ubuntu.com precise-updates/restricted TranslationIndex [71 B]
Get:20
http://archive.ubuntu.com precise/main Translation-en [726 kB]
Hit
http://archive.ubuntu.com precise/restricted Translation-en
Get:21
http://archive.ubuntu.com precise-updates/main Translation-en [42.5 kB]
Get:22
http://archive.ubuntu.com precise-updates/restricted Translation-en [267 B]
Fetched 2,350 kB in 2s (1,120 kB/s)
Reading package lists... Done
ubuntu@ubuntu:~$ cat /etc/apt/sources.list
# /etc/apt/sources.list
deb cdrom:[Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)]/ precise main restricted
deb
http://archive.ubuntu.com/ubuntu/ precise main restricted
deb
http://security.ubuntu.com/ubuntu/ precise-security main restricted
deb
http://archive.ubuntu.com/ubuntu/ precise-updates main restricted