Duplicate content on Yahoo

How do I prevent 2nd domain from being indexed?

[namniboose]

I've just realised that Yahoo has indexed a domain name that is pointed at our website.

I have tried to be very careful to make sure that there are no links to that domain but someone created an advert for us without my knowledge and linked to the pointed domain.

Anyway, Yahoo has demoted the website and I get no traffic from there any more.

So my first question is: how do I make sure that this 2nd domain is not indexed by Google, Yahoo and MSN?

The redirect is done at the registrar not the server and I thought this would prevent this problem.

Thanks,
Aline

[Quadrille]

Use a 301 permanent redirect from the unwanted site to the 'public' one.