Google statement on missing pages (410 vs 404)
 

The Question:

This is my first experience with a web presence and an own online store. I have set it up and ran it for a few days in test mode online and somehow it happend Google picked the site up and indexed it. About two weeks later my store was ready for real life and meanwhile I also added a tool that creates short SEF url's. Now I see in webmastertools I have more than 1450 404 errors because all my pages have gotten new urls. Well, someone told me not to worry too much about it and Google will find the new urls and delete the old ones. If that's true, time will tell. But the real problem I'm having is, whenever I have to update the inventory of my store (several times a week) I mostly have to delete products they got discontinued. This can be between 5 or in times like before Christmas or in the Spring even 20 or more a week. This means in worst scenario 20 or more missing links = 404 Errors. Is there any way to prevent that? Any time I update the inventory I have all urls generated new and also my sitemap gets created new with the current inventory. I can imagine having 404 errors in the report on a regular basis will in the long run be negative for my PR that I'm trying so hard to build up.

THE ANSWER:

I followed up on the 404 vs 410 thing with the team here. As mentioned by some others here & elsewhere, we have generally been treating them the same in the past.

However, after looking at how webmasters use them in practice we are now treating the 410 HTTP result code as a bit "more permanent" than a 404. So if you're absolutely sure that a page no longer exists and will never exist again, using a 410 would likely be a good thing. I don't think it's worth rewriting a server to change from 404 to 410, but if you're looking at that part of your code anyway, you might as well choose the "permanent" result code if you can be absolutely sure that the URL will not be used again. If you can't be sure of that (for whatever reason), then I would recommend sticking to the 404 HTTP result code.

In the worst case, the 410 will be treated the same as a 404; in the best case it'll be a bit quicker & stickier :-).

Source: http://www.google.com/support/forum/...ac47&hl=en#all