From what I hear google is able to tell if you own those sites. The only methods I can think of are the following:
- Same IP
- Whois information
It's easy enough to change your IP, just contact your host and you'll pay a bit extra for another IP, however your whois information has to be accurate, and so you'll have a harder time with that. Really it doesn't matter if you own multiple sites, but this only becomes an issue with people want to link to themselves. Bar that, you'll want to have good loading speeds, preferably an IP in the same country as where your visitors are coming (I really don't see much importance in that, but if people say it, it must be for a good reason.)
In my opinion, good SEO comes with lots of hard work. There are many things you can change, such as file names so that they're more descriptive. meta tags (from the few SEO videos I've seen by google, them seem to suggest that they often 'look over' the tags, however they do use the site description, provided it's accurate.) You're better off in my opinion with lots of keyword rich blog/website posts.
PatrickMS is pretty well right-on. Multiple sites at one host is fine. The head of Google's webspam team (Matt Cutts) keeps a blog and attends various SEO conventions, and has repeatedly said NOT to get separate IP's for your sites-
Years back, it used to be much easier for people to maintain massive rings of domains, and interlink them. I believe that's when blackhatters started talking about disguising these huge networks of domains a lot (differing whois, IP's, data centers, site designs, and content style amongst them). There are still people that maintain content farms like this, but it seems to be incredibly less with time, and is only getting harder.
If you want successful SEO in the long-run, remember to always look at it from the "if i were google" perspective. Build a high quality site and lots of high quality backlinks and you'll rank well for a very long time.
Corey Northcutt | Northcutt Competitive inbound marketing with a hosting industry competency. Social | Content | Optimization | Outreach
Given Google's penchant for statistical methods, trying to do a run-around like that isn't worth it as they can easily use statistical inference on any group of websites and their content to determine whether they're likely legit links or part of a network.
Physical topology doesn't play a role anymore, and that's why you're seeing more and more, a focus on random forum replies everywhere with non sequiturs but otherwise have the right keywords and correct grammatical structure.
As what I know and what I did for my client who has 100 autoblogs is that I pointed 3-4 domains which are on different niches on one IP so that it won't look as if you are dominating a particular niche. As far as I know, when Google ban your site, it will possibly ban other site pointed on that IP.