Sod:
As the guy that holds the keys to the kingdom, so to speak, I can do a whole heck of a lot with the permissions that are granted to each andevery forum member. I can, to answer your question, block someone by IP address, and also by email, by sign-in name, and a few others,. I can "ban" said user for any length of time (up to permanently), and can leave a message to other "administrators" (assuming that I have designated such) as to why I've chosen to ban someone. I can choose to havAnd on, and on. I can even make the machine automatically censor any words I choose, turning dee ay em en into truckstop or rutabaga or whatever I want.
There's your specific answer. Now, to the unasked question about whether any certain individual is banned at any specific moment: That's information that I don't feel is appropriate for me to divulge on line. I don't care to have people talk about me when I can't respond, and I grant that same consideration to each and every member of this forum.
Best wishes, and thanks for being a member of the landracing.com Forum.