Banned Users =/= Banned IPs

There are 6 names in my banned users list. This is good.
There are 6 IPs in my banned users list. Also good.

The problem is that the two do not match. One of the six banned IPs is a poster that no-one banned. They are also the only one who has used thier IP. Additionally, two of the people who were banned have IPs that are not on the list at all. There are also a few who needed to be banned before making a post... so I don't have an IP address for them.

Also, there are IPs that are banned that I don't know who's account they are attached to... is there any way to "reverse lookup" these IPs? I'm afraid of who I might be letting back in if I just lift those IPs without knowing how they got on the list in the first place.

Hello.

The problem with Ips is that the most of the time, the change : for example, actually, my IP is "***.123.**.**" and tomorrow, it will be : "***.111.**.**". That's why it's dangerous to ban an IP, you can have the IP which is banned and be banned whereas you are the founder of your forum !
You should use the ban with the profiles

This change of ip's happens only to those who have dynamic ip. I don't have a dynamic ip so my ip doesn't change. But the best way to avoid this is to do exactly what Max said: Ban the profile not the IP

the only other way is,
if the unwanted person has a unique hostname, you can ban hostname, if it isnt unique, then anyone using same host/ISP will be banned also

If I understand this correctly, if the banned people (if I use a profile ban) use a different email address, name, etc... then they can return to wreak more havoc, right?