In most cases, a permanent 301-redirect is your best option for pointing one domain at another. If you have many inbound links from abcd.com and defg.com, you will likely want to redirect these all over to your primary site, abc.com.

If you have the time and devotion to creating unique, useful content on all 4 of your domains, then I would likely not recommend a redirect to the original page, and I would just use anchor text linking to link all your secondary pages to the page you wanted to carry the most weight online (abc.com, in your example).

Redirecting is a touchy subject, and in most cases 301 redirects are preferred to ensure that the sites you are redirecting to are ranking the best in Google searches. However, please keep in mind that a 301 redirected site will not be visible by users or search engines, so any unique useful content you may have created on that page will be lost once the page is 301ed to another page.

I hope this helps Mark, and please keep checking back with your blog for helpful tips, tools, and advice on SEO and everything internet marketing-related!

Thanks for the helpful post on the redirects.

I would like to know as how Google sees if we simply redirect the Domains and not duplicate content i.e. not hosting the same content for all domain.

Lets explain this by an example.

I have purchase 4 domains from Godaddy

1) abc.com
2) abcd.com
3) defg.com
4) xyz.com

My main hosted site is abc.com and I have redirected all other 3 domains towards this domain using the Domain control panel provided by Godaddy and redirecting the the URLs to abc.com

So the summary of my question is that “How this affects my Google ranking or SEO efforts”

I look forward to your helpful answer on this.

Thank you,
Mark