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IP Subnetting Made Easy (read very good) - http://www.techrepublic.com/article/ip-subnetting-made-easy/6089187
Enter an IP address to find out info of the owner and what Internet address block they own - https://www.arin.net/
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IP Subnetting Made Easy (read very good) - http://www.techrepublic.com/article/ip-subnetting-made-easy/6089187
Enter an IP address to find out info of the owner and what Internet address block they own - https://www.arin.net/