Here is an SEO myth that has not really been proven one way or another yet
. The myth is that having links from the same class C IP address will not help you. If you don't know what I am talking about here's how you breakdown an IP address.
So where the CCC is that number needs to be vary. The reasoning behind this is that someone could get web hosting and put 1,000 different sites on it and then link them all to one site trying to gain its link popularity. So the search engines put an end to that by using the IP of the sites to calculate how much weight to give the link.
There are quite a few people that don't believe that this myth is true just for the simple fact of how popular shared hosting is. If this myth is true then all those sites on the same shared hosting server cant help each other out with ranking.
There is some evidence that can prove this myth though. I have followed many discussions on this topic and have seen some results that make me a believer. The results basically just prove how a site with far less links can out rank a site with a ton more links. This is because the site with less links has a ton more different class C IP's links than the one with just more links.
Like I said I am a firm believer in this myth and I don't even like to refer to it as a myth but until proven beyond a doubt I will call it that just to make people happy. So when you are doing link building be sure to check out the IP address on where your link will be placed in order to make sure your link will pull the most weight.