You may wish to check the IP address(es) of your posts. To do this, you only have to change your forums theme (Profile > Look and Layout Preferences > Current Theme) to anything other than ff or the default. After doing this, the IP address logged to each of your posts is displayed in the bottom-right corner of each post.
Assuming you make all your posts from one location, the IP address will always be the same if you have a static IP. If they are different, you have a dynamic IP. Depending on your Internet service provider, you may or may not be able to get a static IP.