As the title suggests, is this bad for SEO? If so, how bad? What can I do to change this? Any good hosting providers? Thanks.
It's not the fact that if all the sites are on 1 server that's bad, it's whether or not they are linking to each other trying to pass around SERP weight. If you are legitimately building links, there shouldn't be any problems.
So I am guessing that these sites are not sharing links. However, say 50 sites out of the 4690 share links with each other and say 100 of them are bad, malware sites. What would this do?
i would say it doesnt affect your serp's at all...I'm actually surprised your host allows that many url's! I use host monster and they sent me an email saying i had too many files on my server so i went and deleted a bunch of stuff i wasnt even using.
It will not affect your serp unless all these websites point to your website. There is no way you can change unless your website get a unique ip.
Ah I see, thanks everyone. If I had to choose hosting again, I'd choose some type of SEO hosting with Class C IP's.
It is no longer that big of a deal to have a network of sites sitting on one machine. You should still maintain the same inbound/outbound link assertions of things when you think about link building but google is daft enough to realize that folks host lots of things on the same machine. http://forums.searchenginewatch.com/showthread.php?t=9408 should explain your c class question. hope that helps, Nigel
If you have too many other sites on the same C class IP, then as llong as you are being legitimate its not a problem. But if some of the sites are spammy (which your web host will detect and disable) then you may be penalized for being in the same link neighborhood.