I have noticed a bot trying a brute force on one of my CMS's. When I try to add the IP address with

iptables -A INPUT -s 91.207.6.154 -j DROP

it shows in iptables as

DROP    all   --   154.6.207.91.unknown.SteepHost.Net   anywhere

and the ip is still able to connect to the server. Am I doing something wrong with adding the IP? Can I add the IP and not have the host for that IP show in iptables? Maybe that has something to do with it. Thank you