Actually the period at the end is part of the DNS standard, without it, your machine's search path is searched first (e.g. in resolv.conf on Unix/Linux) So if

Actually the period at the end is part of the DNS standard, without it, your machine's search path is searched first (e.g. in resolv.conf on Unix/Linux) So if your ISP is AOL, you might have a search path of aol.com so looking up "to" will first try to.aol.com if that exists it will go there. Putting a "." at the end will let it go straight there. This isn't normally a problem because it's not like aol is going to set up google.com.aol.com. But really everyone should have periods at the end of domains.