The Class C Checker tool allows you
to check whether some sites are hosted on the same Class C IP Range.
You might want to use the Class C Checker if you own several cross-linked
sites. If you do, it may be more efficient (for SEO purposes) to
host them on different Class C IP ranges. Additionally, if you are
going to get new links from different sites, you may want to see
whether they share the same Class C IP range. Again, this could
make a difference for SEO purposes.