Hi Ksuth,
Based on the information you post, I want to confirm some information with you:
Do you mean you try to configure the IP address for your public website in Microsoft Office 365?
If it is the case, to resolve this issue, please take one of the following actions:
l If the IP address is incorrect, enter the correct IP address, and then click Next.
l If the IP address is correct, click Next. When you are prompted with a warning message that states, "Are you sure you want to continue with this IP address," click Yes.
For more information, you can refer to the following article:
http://support.microsoft.com/kb/2651177
If you do not have a public website, please select “No” when you add your domain to Office365. Please refer to the following picture:
Thanks,
Jason Jiang