Domain Masking is usually offered by the registrar as a service.If you set up domain masking for a blogspot blog, For example domain is a mask for

When someone open is really forwarding  to without change in address in the address bar.The user continues to see in the address bar although the site and its contents are really from

Why use domain masking?

If you have an existing site that is hosted for free (such as Blogger or blog) to be able to give a short URL or address can be an advantage for you. Even if you are not willing to pay for hosting, which is a fast way to use your domain name.

Why should I think twice before masking domain? What is important?

It is certainly important to Google. If you rely on search engines for traffic, then you should seriously consider if you need to use masking domain name or if you can find another solution. As Domain Forwarding or change your web hosting

Google does not like duplicate content and masking the domain, shows two domains with exactly the same content. What will happen? Google has not released exact policy masking, but it is clear that only once duplicate content indexing, and not the URL or domain that you prefer.

I still want to use domain masking. What should I do?

Make sure you use if given an option to manage your domain name. 301 redirects (permanent)

It may be possible to do this in the settings when you select mask, domain, or the access to the management console server, so it is possible that this will not be available to you.