A few months ago, we started a new version of our website. We also changed our domain name to be more in context with our company.
The website was updated during last weekend and the old version was shutdown. Unfortunately we found out that no redirections had been made whatsoever. So we were completely invisible to the internet. All links pointing to us was showing a DNS error in the client browser. Speaking with the company that was handling the situation, they decided to bring back the old website online.
The new domain that we are using had been penalized by google 7 years ago because someone bought fake traffic leading to it.
The company is now advising us to run both website and buy ads for both for a certain amount of time. According to them, this should help us spot if the new domain is still penalized. Although the new domain is already indexed on Google and shows up as a 3rd result for our keywords. I find it hard to believe that it is still penalized.
I'm looking for second toughts as to know if what is being suggested to us is safe and good practice, if not, should we just move the website with all the redirections or does anyone have other recommendations?