I am trying to update my ubuntu with "sudo-apt-get update"
Below is the error I am getting. Kindly help me resolve.

$ sudo apt-get update

Err http://security.ubuntu.com precise-security Release.gpg                                                                                           

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Err http://ppa.launchpad.net precise Release.gpg                                                                                                      

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Err http://ubuntu.mirror.ac.ke precise Release.gpg                                                                                                    

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Err http://ubuntu.mirror.ac.ke precise-security Release.gpg                                                                                           

  Unable to connect to 172.16.63.15:3128:

Err http://ubuntu.mirror.ac.ke precise-updates Release.gpg                                                                                            

  Unable to connect to 172.16.63.15:3128:

Err http://extras.ubuntu.com precise Release.gpg                                                                                                      

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Err http://archive.canonical.com precise Release.gpg                                                                                                  

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Err http://apt.insynchq.com raring Release.gpg                                                                                                        

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Err http://dl.google.com stable Release.gpg                                                                                                           

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Err http://toolbelt.heroku.com ./ Release.gpg                                                                                                         

  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

Reading package lists... Done                                                                                                                         

W: Failed to fetch http://ubuntu.mirror.ac.ke/ubuntu/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Failed to fetch http://archive.canonical.com/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Failed to fetch http://apt.insynchq.com/ubuntu/dists/raring/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/precise-security/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Failed to fetch http://ubuntu.mirror.ac.ke/ubuntu/dists/precise-security/Release.gpg  Unable to connect to 172.16.63.15:3128:



W: Failed to fetch http://ubuntu.mirror.ac.ke/ubuntu/dists/precise-updates/Release.gpg  Unable to connect to 172.16.63.15:3128:



W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Failed to fetch http://toolbelt.heroku.com/ubuntu/./Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Failed to fetch http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out



W: Some index files failed to download. They have been ignored, or old ones used instead.

W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-amd64_Packages)

W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main i386 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-i386_Packages)