http://canon/ would refer to whatever canon was local to your gateway's DNS host record (I believe; I can't find the exact term for it.) For example, my computer is d207-6-247-238.bchsia.telus.net. If I type "canon" into anything that calls gethostbyname(), it assumes I mean canon.bchsia.telus.net. When that doesn't resolve, then it tries "canon."

http://canon./, on the other hand, refers to the "canon" that is located at the "root directory" of the internet—that is, ".". Most addresses don't need this, because once you specify any more than a host name, it assumes the rest of the domain "path" is a fully-qualified DNS record, and doesn't bother checking your local network for it.