domain forwarding and masking

I've recently been contracted to perform some SEO work for a local realtor, and one of the first things that I discovered was that he had several different domain names pointing to his homepage. In most cases, this is a good thing, as long as you aren't masking your domains. In other words, if you type in one of your alternate domain names, it should forward the visitor to your real site, and display the real domain name, not the alternate name.

If it still displays the alternate domain name upon reaching the site, you run the risk of being penalized by Google for duplicate content (or what is essentially a duplicate website with the exact same content as your primary site).

So what is domain masking good for? Aside from spammy type applications, masking is great for pointing domains names to sub-domains that may otherwise be ignored by Google. However, you still need to make sure that the subdomain in question doesn't get indexed as having the same content as the masked domain. Your best bet, if it is available from your hosting company, is to opt for what they call an "add-on" domain. It automatically creates the subdomain and sets the domain to point to it. Most cpanel packages feature this. If yours doesn't, you can ask for it (or find another host).

Using multiple domain names is *very* common in the real estate industry. I wonder how many of them are hurting their search engine ranking by using masking features to serve up duplicate content.