It doesnt really matter as long as youre not using your different domains to link to each other. If you are going to be using your domains as backlink pumper sites you need to have separate C class ip hosting.

Think about how many thousands of sites are sharing ips on the typical shared hostgator accounts? Google doesnt care unless they detect a linking pattern.

yeah it doesn't really matter, but on my end, as I am using a dedicated server having my other domains to help my new ones which is on the same server somehow helps. I mean, hey not everyone has money to pay for a separate hosting with a different ip specially the startups.

Yes its matters shared hosting on your SEO efforts but not too much becuase small sites can not errort dedicated hosting for his site thats why it doesn't matter.

yes RealEcon i agree with you if we host so many domains in one server ip than google will detect as "unnatural" . but when your using one server that time you have to use different IPs for Different Links