I have just installed Ubuntu 12.0.4 LTS (Precise Pangolin). I tried to run
sudo apt-get update on shell and it ends up with following errors after couple of seconds:
Err http://pk.archive.ubuntu.com precise Release.gpg Could not connect to pk.archive.ubuntu.com:80 (18.104.22.168), connection timed out W: Failed to fetch http://pk.archive.ubuntu.com/ubuntu/dists/precise-backports/Release.gpg Unable to connect to pk.archive.ubuntu.com:http: W: Some index files failed to download. They have been ignored, or old ones used instead.