Here's my case: I have a website and it is indexed by Google. I have not built any links for this site, but it is indexed, as I run ad Adwords campaign for it sometime before. I have banners on two of my other sites that point to that site, but they are nofollow, so actually there are no any backlinks built for that site. And I want to create a new site with the same content (the main reason is a new, better domain). So I'd like to get the current site deindexed from Google (using the robots.txt file and deindex it from the webmaster tools). Then when it is already deindexed, I will start the new site with the same content. Can my new site get a duplicate content penalty (even if my old site is deindexed)? Also, I wonder how long does it take to get a website deindexed from Google when submitting a request through the Google webmaster tools?
Yes that might happen, you should create the new site and then redirect the old URL to the new. Deindexing may need some month, I observed variations between 3 and 9 month.
i don't know if your method will get a duplicate content penalty but using http 301 redirects to point your old site to your new one is a safe way of shifting content to a new site plus you'll retain any credit google gives for the age of the content. Ideally you'll use a seperate redirect for each page but if that's not possible just redirect the whole site.
Yes i agreed buy using 301 redirect you can redirect your old site to new site and get benefit for age of content.
Thanks guys for your replies. However, I still would like to do that for a certain reason. Any other opinions?
I personally would worry to much about duplicate content, if the old site had no backlinks and you going to do some good promoting on the new site just do as you first said and remove all the content and ask for it to be removed from G's index via your webmaster account. If the original site has PR or backlinks etc 301 redirects would be the way to go.
yes i agree 301 is the best option.(HTTP 301 status code is used to indicate that a page has permanently moved)
You will waste some google juice and credit if you just start everything from 0. Set up the new domain, set up all the pages, and then 301 redirect the old domain to it. That's the best way of doing this.