Difference between 127.0.0.1 and 0.0.0.0 in the context of the Firefox address bar

Question

I need to configure a firefox extension to load a page that can never exist. It should be as fast as possible. The obvious choice is about:blank, but the catch is that the API used by the extension requires the http protocol. That appears to eliminate the possibility of using about:blank.

The obvious candidates are http://0.0.0.0 and http://127.0.0.1 (the latter of which is the loopback address, and should be the same as http://localhost).

In this specific context, what is the difference between using http://0.0.0.0 and http://127.0.0.1?

What I've read so far (but none directly answer the question for this specific context):

• What's the difference between 127.0.0.1 and 0.0.0.0?
• Netstat -a command : Difference between 0.0.0.0 and 127.0.0.1
• https://stackoverflow.com/questions/20778771/what-is-the-difference-between-0-0-0-0-127-0-0-1-and-localhost
• http://www.faqs.org/rfcs/rfc3330.html

Answer 1

In this context, what is the difference between http://0.0.0.0 and http://127.0.0.1?

I need to configure a firefox extension to load a page that can never exist. It should be as fast as possible.

That rules out using http://127.0.0.1 as you cannot guarantee that a page will not exist (I'm running a server on local host for example).

There cannot be a server running on 0.0.0.0.

Using Firebug gives us the answer.

http://0.0.0.0 is much faster regardless of whether there is a server running on 127.0.0.1 or not.

Case 1 - http://0.0.0.0:

Case 2 - http://127.0.0.1 (no server running):

Case 3 - http://127.0.0.1 (server running):