So, you need to find all broken links within a site. In this article, I would offer you a few solutions to do that.

Links checker module

http://validator.w3.org/checklink – checing one node. You can download the source code here.
https://addons.mozilla.org/eng/firefox/addon/532 – Add-on for FireFox
http://linkchecker.sourceforge.net/ – script that works for Mac OS, Windows and Unix.

Links checker module

Download the module here: http://drupal.org/project/linkchecker
Install it, then open settings page: http://example.com/admin/settings/linkchecker
Set the module. Set resetting results when Cron is launched. You can also uncheck “Consider only fully qualified URLs ( not local links )” – then you will check as interior as well exterior links. By default, the module checks exterior links only.

Settings page for the module
Run cron manually (http://example.com/admin/logs/status/run-cron)
Open in browser: http://example.com/linkchecker/report

Report page of Links checker

Note: If a site isn’t located in a web-server root and you have Links checker v 1.12 or less, then you will need to change the module code to provide its correct working: http://drupal.org/node/244368

Good luck!