Links which ends with 404 Error are automatically stored in the database (if it is set in parameters). If you click on the link, you can add new link (where the site should be redirect). For successfully redirecting of the site the link must be published. Add the links in following format:
It means, without https:// and without the right slash (/)
If you click on Purge all obsolete links which don't have associated new link will be removed.
Count (NR) - count of accesses to site which ends with 404 Error (redirect is not set)
Count (R) - count of accesses to site which ends with 404 Error (redirect is set, the site will be redirect)
Here the referring sites, which contain wrong links to your site, are stored. If the referring site is located on your server, you can easily fix wrong links on this site.
If you click on Purge all referring sites will be removed.