If your site is currently treating unavailable pages (404 errors) like temporary redirects (302 redirects) you may not have any problems with the search engines but your site is losing out on some important advantages of a proper 404 error.
The Way a 404 Normally Works
This is how a 404 normally works on a website when a search engine, let’s use Google, visits a URL (i.e address) on your website that cannot be found that was previously spidered/indexed as functional:
- The visit produces a 404 error from the server.
A 404 error is provided by your server when an Internet client (i.e. a browser, search engine, etc.) reaches a URL on your site that can not be produced by your server because it is no longer there or it is incorrect. - The first time Google encounters this 404 error, it does not remove your URL but it takes note the page is not available and the broken link/missing address will be mentioned in your Google Webmaster Tools dashboard for you to fix ASAP.
- The second time Google encounters the 404 error it is a good bet the page will be removed from its index and the error will remain in your Webmaster Tools dashboard for fixing. Google will continue to find the broken link until it is fixed, at which point any associated rankings you had for this page can work their way back up to where they were.
Using a 302 Redirect Response Instead of a 404 Error Response
Here is the situation: when a search engine visits a URL that no longer exists, your server delivers a 302 redirect response instead of the proper 404 response. ... discover the best solution for 404 errors
