Hello, If you change a website completely loosing all the current urls search engines (mostly google) are going to punish your website or it will re-index everything ?
it will eventually reindex everything, but if u had good rankings before for certain keywords u will lose that. so best to do a bunch of 301 redirects
If you don't do a redirect, then Google will likely put the new pages into the supplemental index for a while as they have the same content as the older pages in its index. This happened to an early site of mine and I ended up having to rewrite the new pages over and over - never again!!!!
For links that will not exist anymore and won't redirect them manually, can I just redirect on 404 error to main website url? Thanks for the replies.
Look at Qondio they used to be Qassia and were page rank 5 with a ton of trust rank and alexa. Once they changed, all their URLs changed and now they are pr2. I had nearly 200 links there some were pr 3-4 now they are all pr0