I have read on other forums that the age of a website may be one of the factor in Google algo.

I am trying to optimize my website, but the url I am optimizing is an ALIAS (rich keyword), since I have more then one Domain name pointing to the main server.

When I try to look at the age of my website with different tools, It seems that my website have no age!

My questions are:
1. Do I have to change my main domain name for my Alias (with Rich keyword) as the principal Domain name?
2. Is there a good reliable tool to find the age of a website?

Yes, in my experience age is a factor, that is what is known as the "sandbox" effect. It often lasts as much as 12-14 months.

To benefit from the keyword rich domain name, you will need to change your main domain to that, and then have permanent redirects set up on any aliases you have.

With regards to finding the age of a site, maybe just look up the date of the domain registration. You can do this at many sites such as http://www.nsiregistry.net/whois/

Age seems to be a factor only to a point. I think that as long as your site is not in the sandbox, then age is pretty much insignifigant.

The age of links coming into your site may be another story.

age is a huge factor. Not only to determine which sites are created for link spam, but for who is dedicating time and effort into a domain. Register the domain for more then one year. I stick with at least 3.

waybackmachine.org is a great way to see how long a site has possibly been indexed for. A domain is as old as its first crawl to Google.