From Online Manual
In most cases, the Repair Settings Tool can detect the correct value for each of the fields and settings listed below. The tool will display a link under each item with a recommended value; clicking these links will update the corresponding text box fields with the recommended value. If you want the recommended value to be used for all of the settings on the page, scroll down to the bottom of the page and click on the link Restore all settings. Be careful though, because SMF will not always guess the values correctly if the server is configured unusually.