The httpinterface supports various pages, but there is no description of these pages and what modes (rest, jsonp, http) they are allowed in. This is a direct response to SERVER-11707.

Examples of pages that require rest:

http://localhost:28017/_commands
http://127.0.0.1:28017/databaseName/collectionName/

Examples of pages that do not require rest:

http://localhost:28017/_status
http://localhost:28017

This means that we see the following behavior when rest is not enabled:

These work:

http://localhost:28017/_status?jsonp=true
http://localhost:28017/_status

This does not work:

http://localhost:28017/?jsonp=true

Some pages that do not require rest can be used with jsonp even when rest is not enabled, but not all of them (see description for SERVER-11707). None of the pages that are linked from "localhost:28017" work without rest, which I think is part of the issue. I also don't see documentation for this "_status" page, so I don't know what the intended behavior is. There's actually a separate "serverStatus" page, which does require rest.