[aexaey]

  1.2 -> 1.0.0.2
  1.2.3 -> 1.2.0.3

But then, much of software would fail here - Firefox/Chrome for example would both threat that as bareword and redirect to search page.

[oneweekwonder]

It work as expected if you give it the http://1.2.3 schema prefix.

The input bar is a search bar in modern browsers.

[exikyut]

Or if you follow it with a trailing slash, for less typing

  1.1/

[WorldMaker]

Or if you prefix it with //

  //1.1.1.1

It's one more letter than a suffix, but as a prefix its a bit clearer. I've known companies to post LAN hostname addresses that way, and in written/printed materials it stands out pretty clearly as an address to type.

It follows the URL standards (no schema implies current or default schema). Many auto-linking tools (such as a Markdown, Word) recognize it by default (though sometimes results are unpredictable given schema assumptions). It's also increasingly the recommendation for HTML resources where you do want to help insure same-schema requests (good example cross-server/CDN CSS and JS links now are typically written as //css-host.example.com/some/css/file.css).