Before implementing a long-term block on an IP address with a long history of vandalism , please check if it is shared by performing a WHOIS and Reverse DNS lookup query on the IP address to determine if it belongs to a school or a proxy server . Before implementing a long-term block on an IP address with a long history of vandalism , please check if it is shared by performing a WHOIS and Reverse DNS lookup query on the IP address to determine if it belongs to a school or an ISP .