2. domain
           This is a partial or complete domain name for which
           the cookie is valid.  The browser will return the
           cookie to any host that matches the partial domain
           name.  For example, if you specify a domain name of
           ".capricorn.com", then Netscape will return the cookie
           to Web servers running on any of the machines
           "www.capricorn.com", "ftp.capricorn.com",
           "feckless.capricorn.com", etc.  Domain names must
           contain at least two periods to prevent attempts to
           match on top level domains like ".edu".  If no domain
           is specified, then the browser will only return the
           cookie to servers on the host the cookie originated
           from.