Blacklisting IP - BruteForce CPanel

Hey Guys, I am looking for some help here.

I got a bunch of emails saying IP:fixed-203-240-87.iusacell.net is repeatedly attempting to login to my website.

So i know what BruteForce is...And I know how to Blacklist an IP from the settings.

My question is...what is the IP Here?

It would let me add "fixed-203-240-87.iusacell.net", it wont let me at "203-240-87.iusacell.net"

What is the IP to block?

In my email theres a link that says click here to black/white list, but It just takes me to a blank page.

Thanks in advance guys.

They are trying to login to cPanel or just your website?

If its just a website, you can add their IP to .htaccess with a deny from xxx.xxx.xxx.xxx command

if they are trying to login to your cPanel, you must login via WHM and add the IP to the firewall blacklist