I think, it is not helpful to register multiple domains and redirecting them on main domain or blog. Besides it, you should promote your original .com blog with help of expert's suggestion like Neil Patel, Brian Dean etc.

Owning extra domains will not increase ranking unless you plan to build unique sites for them all.

Assuming you plan to forward/301 redirect the domains to your main site. If so, Google relies on backlinks, if the domains you buy don't have backlinks, Google doesn't know they exist. You could buy 1 million domains, forward them all to your main domain and have no SEO benefit because Google doesn't know they exist.

If you plan to buy keyword rich domains, build backlinks to them and 301 redirect there is a small boost from the URLs if the domains are of the format keyword-phrase.tld and you are targeting Keyword Phrase on your home page.

However, this means building links to a domain that 301 redirects to the main URL and 301 redirects cost/waste ~15% of the PageRank gained from the links. It's not worth the cost of buying domains and loosing ~15% of the PR for what is a small boost from the keywords in the domain names.

Search SEO Gold in Google, you'll find my site at the top because I'm 301 redirecting seo-gold.com (my old SEO services domain) to my theme site. The SEO gold domain has a decent number of backlinks, the ones I have control over I'm changing the URLs to the new domain and in 5 years time will let the old domain expire IF there's no important backlinks left (few people search for SEO Gold).

David

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You buy up those domains if you have a brand - for example Coca Cola doesn't want someone else to own cocacola.net or cocacola.co.uk - I think this was a bigger deal 10 years ago.

There is absolutely no SEO benefit in owning multiple extensions of the same name unless you have a brand and you are trying to prevent others from registering a domain name similar to yours. 301ing them will do zilch for your site.

It's not a good idea to have multiple domain extension.. unless your website is a giant company that need all shapes of domain extension. In fact, it doesn't help improve your SEO. Try to put a focus on your content and do a safe way of link building. Cheers!

No,it does not works.please focus on your main .com site and do its seo.it really help u.

Yeah, sure. It will work for improving SEO.

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If you are planning your business for different countries your domain extensions may help. For example for a global business .com would be preferable and for a UK business .co.uk would be good.

I don't think it will improve your SEO. I would suggest you to work on your .com domain to increase traffic.