Not sure if this is where you where you're heading here, but when my browser (Firefox) can't resolve ab.ca, it tries to resolve www. ab .ca (spaced so it isn't turned into a non-working link) and then displays an error message as that still doesn't resolve.
As I noted, it's not treated as a URL, because it's a domain suffix. Try to navigate to mb.ca (Manitoba) or on.ca (Ontario) or co.uk or com.cn or similar public suffixes, and the browser will treat them the same way.
However, you can override this behaviour, by typing in the "http://" too, e.g. type in: