I have registered a few accounts/usernames to get my forum going.
I looked up my IP address, which I thought would be the same fo each one but it is not.
All registrations were done on the same Pc with the same internet connection.
Strange or normal?
IP addresses for personal use are dynamic ie. variable. It is to make optimum use of a limited number of IP addresses relative to the number of folk who want to use the internet.
In contrast, a static (fixed) IP address would be used by companies who wish to install routers from which hosts (computers, printers, etc) can be subnetted. Last time I looked the cost of leasing a static IP address was between 1,300 and 6,000 Euros per annum.
In short, what you're seeing is perfectly normal. :)
So how does Twitter, or a forum owner, give the details of anonymous posters who libel others when ordered by a Court?
You would also have their server info and an e-mail address. OK, all of that can be spoofed but if a court orders you to supply that info then give them what you've got and a specialist (ever seen NCIS? ;) )can extract what they need via your machine if necessary.
Having said that, any info is useful as invariably these types work to a (subconcious) pattern and the police have a specialist unit which can track them.