what is the default passcode of ipad 2, what is the default passcode of ipad 2

There is No Default Passcode...

If you cannot remember the passcode, you will need to Restore your device..

Connect the Device to the iTunes library you Usually Sync with, open iTunes, click on the Device tab that appears in the Left side column of iTunes, Select your Device, then go to the Summary Page and click Restore.

If necessary Place the Device into Recovery mode...

See Here...

http://support.apple.com/kb/HT1808

These links should guide you through it -

http://support.apple.com/kb/HT1212

http://support.apple.com/kb/ht4097

There is no default. You will have to plug your iPad into iTunes and restore as a new device.