Class C Ip checker is used when you want to host multiple websites. You can check duplicate ip addresses and Class C blocks from the same hosting.
Hosting multiple websites on the same ip address can harm you website ranking in the search engines. Also this tool is very useful when you get some backlinks from other websites. If all websites that are linking to your domain have same Class C blocks then it not good for ranking.
If you have hosted your website on the same company servers then there are lots of chances that you will get same ip addresses. No doubt it will not harm your ranking, but if you are getting links from that hosting then it will affect your ranking.