Main domain on server vs. addon & SEO effects?

[mediaadvantages]

This post is deleted!

[pabloandres]

Technically, addons domains work exactly like main domains at visitor level, having no impact on SEO.

[sesertin]

I see that site is fresh as content cannot be found in google, so I don't know which of the following are you using: You can have add on domains in two ways:

• content is published on the addon as well: not good as you are duplicating your own content
• addon  is redirected to the main domain: This way content is only indexed on the main domain, so if you change the main domain  and the addon, the presently main will disappear from SERPs and the one which is presently the addon will appear

Bottom line: if you do it right content will only be visible on one domain. Decide which one would you use, build your links to that one and market that one. Other domains only come to play if they are exactly matching one of your search terms so that you can build microsites on those. This is only good for companies with lots of resources as working on multiple domains is always harder and more time consuming than working on one.

[FergusonSEO]

I personally think add-on domains are not good for SEO. I have had 2 sites as add-on domains to another site for 2 years now and they have never penetrated the SERPs. To date, I have only used add-on domains for sites where ranking isn't important (example: my wife's blog).