custom 404 pages - must return 404 code?

If a site is completely revamped, so most of the old URLs will no longer exist, putting a custom 404 page in place seems to be a sensible option, so when visitors visit (e.g. using search engine links to old pages) they get a professional looking "sorry not found" message.

I've seen some 404 pages that will actually return a 200 code - i.e visitor requests page "old_page.html", and a 200 "all OK" code is returned, while the custom 404 page "not_found.html" is displayed.

What are the pros and cons of returning a 200 "OK" code, versus a 404 "not found" code in this situation?

In terms of the problem of search engines having all the old pages indexed, if the custom 404 page actually returns a 404 code, does this speed up the process by which the search engines clear out old cached content that no longer exists?

Howard

 

I certainly believe that you will speed the process up with the return of 404 instead of 200.

I think that if it returns 200 the pages will end up in Google supplemental instead of actually being deindexed. That's what happened to me anyways.