How do I keep Google from indexing my redirect domains?

I have five domains redirecting to my main site. I originally setup these redirect domains because many people in my target demographic are not very computer literate, and I worried they would mis-spell or mis-type the site name. I want to do what Google does with gogle.com and their other domains.

exampledomains.com <-- Main Site
exampledomains.net
exampledomains.org
exampledomain.com
exampledomain.net
exampledomain.org

Now I'm seeing that Google is indexing about 3000 results for each redirect domain, and I'm worried it's going to hurt my SEO.

My host setup the domains with the same IP as my main site, then put non-masking redirects in the .htaccess. The sites do not have their own accounts on the server, so I can't setup a separate htaccess or robots.txt as their presently configured. How should I set this up?

 

DNS-records? Why are you doing this on the site-level, instead of in DNS?

 

This is what I'm wondering! It seems like it should all be done through DNS, but I've asked my host twice and they said otherwise.

What's the proper way to set this up? Which of those DNS entries can I eliminate (I obviously don't want to use those default subdomains)?

 

Anyone?

 

What you do is you add for instance a CNAME for the extra domains to the main domain - mostly like the www.domain.com to domain.com (although normally it's the other way around)

 

Thanks @PoPSiCLe

Is that something different than what I have setup above? Looks like the cname is there.