Will search engines discover that our old pages have been 301 redirected if there are no more links to them in the old site?

Question

We've moved our website to a new domain.

Thousands of our pages come from one PHP file in the old site (e.g. oldsite.com/news.php?id=<id>). So we added some code in news.php file to do a 301 redirect to the specific corresponding news article in the new website (newsite.com/news/<id>).

We have not yet done a 301 redirect for the root of the old site (so we could display a notice to our users that we've moved), but all links inside it are already 301 redirected.

My concern is that, when Google crawls our old website, it will no longer be able to find the old news articles and discover that they have been 301 Redirected -- is this correct? If so, does that mean our PageRank won't be carried over to the new site?

I've also read that we would need to create a sitemap for the new site. Is it possible to indicate in the sitemap the old and new locations of specific pages? Because if not, how will Google know? (I'm not sure change of address in Webmaster Tools would be specific enough).

Answer 1

If the pages have PageRank as you mentioned, this means the pages are indexed in Google. If the pages are indexed in Google, then the next time Google crawls the pages form their index they will find the 301 redirects to the new pages.

If the pages are not indexed in Google, then they won't have any PageRank, so you don't need to worry about losing any.

You can't indicate your old URLs in a sitemap.xml file, only your current URLs. You should make sure to indicate change of address in Webmaster Tools as mentioned.