An IP number is required for ANYTHING THAT CONNECTS TO THE INTERNET. Every time your computer connects to an ISP, your computer must either produce its IP number or must get a new one for the duration of the connection from your ISP. The IP number is used up to the connection with the physical device where the information resides, and normal "file/directory tree" structures are generally used to reach a specific file.
With respect to your imagined "error" at mudcat, you need to recognize that a URL that doesn't start with http:// or www is not a complete and legal URL and will be treated as a local link to a bookmark, with the assumption that the bookmark is to a file at mudcat.
Your explanation that "you never made a mistake" doesn't really hold much water, and I think it's time for you to write it off as a "SHIT HAPPENS" incident and get on with whatever interests you.