Back-links from site on same Class C network?

The FAQ indicates that the number of back-links to one's site is positively correlated to search engine rank. But what if the back-link comes from a different site (and domain) that lives at the same IP address as the site I'm trying to optimize? Alternatively, what if it's a different IP address, but still on the same class C network?

Would it be worth my time to place the back-linking site on a different class C network?

Just to be clear, my back-linking site(s) aren't the only ones linking to the primary; There are plenty of other third-party sites too. I just want to make sure that there's no SEO penalty associated with creating links between two sites on the same class C network.

You should not post your links on sites which have same class c network because most of the time its not usefull and a waste of your time. Google will not penalize your site so chill. But you can post your links if they have high PR ranking.