I just responded to a question on the message board that I though a few "RELibbers" might find useful.
The question was along the lines of:
Does anyone know if you can have more than 1 domain point to your primary domain? As I understand it, there is no good reason to mask and point domains, but it is better to re-direct them? I have several domain names and would like them ALL to go to my primary site, but also be searchable on the search engines. As I understand it, masked and forwarded sites don't come up on the search engines. Right?
Here is my answer:
There is a way to have multiple domain names pointing to the same site or page and still remain searchable. But it's not a good idea (at all) to do that. Eventually the search engines will realize there are different domain names pointing to the same site and they will penalize them all (potentially including the main site domain). Penalty could range from lower search engine placement to banning the domain names from the search engines.
They see multiple domains pointing to the same site as "duplicate content". They implement this penalty to keep people from buying dozens (or hundreds or thousands) of domain names and manipulating search results with them.
Redirecting a domain name (properly, with what is known as a 301 redirect) tells the search engines to ignore the redirected domain, and eliminates the dup content penalty.
That begs the question, "What is the point in redirecting a domain name?"
That's best illustrated by an example:
We have a page on our site about a certain area in Phoenix called Whispering Ranch. The address for that page is:
http://www.thompsonsrealty.com/Whispering_Ranch_AZ_Land/page_1365554.html
If I want to put that domain name in an ad, on a postcard or a flyer or a yard sign, or even give it to someone over the phone, it's almost impossible due to the length of the domain name. (just try saying that link out loud like you'd have to do with someone on the phone...)
So we bought a domain name and re-direct it to that page.
http://www.WhisperingRanch.info
That can fit in an ad, be remembered, and is easy to communicate. But it's not "searchable". However, the page itself (the one with the big long domain name) is most certainly searchable. It's #1 in Google for the terms "Whispering Ranch", "Whispering Ranch real estate", "Whispering Ranch land", "Whispering Ranch Realtor", "land in Whispering Ranch" and many more related terms.
So I don't really need "WhisperingRanch.info" to be indexed in the search engines. This page gets plenty of search engine exposure without WhisperingRanch.info being indexed.
If it were allowed to be indexed, what would happen is the exact same page would be showing up multiple times in Googles results, and that's not what Google wants. If they allowed multiple domain names pointing to the same page to be indexed, there would be nothing to stop me from getting 10 Whispering Ranch domain names, pointing them to my page, and having all 10 of those domain names showing up on page 1 of Google. Not that I'd mind that, but I can see why Google doesn't want it that way. I don't want it that way when I'm searching for something. I want to see different options, not the same page over and over just with a different name...
Make sense?
Hope that helps!
Jay