What Is My Local IP?

One of Radio's key design points is its use of (and distinction between) your local weblog and your public, upstreamed weblog. Yet, while distinct, the content of these weblogs is identical. Your public weblog mirrors the content in your local weblog.

(A nuance here: you might decide that a particular weblog category should be published as its own weblog. Still, logically, the content of that public category weblog will be identical to the content in the local weblog category).

Radio can pull this off smoothly because of a neat little standard regarding a particular type of IP (Internet Protocol) address. 

When you launch your copy of Radio, it uses the IP address of 127.0.0.1:5335. You will see this IP when you look in the address field of your browser from your desktop home page:

Just like any IP address, it has four numeric segments, each separated by a dot. However, this has been defined as a very special IP that is known as the 'loopback address'. When your computer sees this address, it know that what it is supposed to do is test its own internal network - not try to find that address on the public Internet.

(For more information the more typical type of public IP Internet address, see What Is A Static IP?)

The fifth item (5335) is actually a 'port number' assigned by Radio. That is not relevant to this particular topic and is not something that most Radio users need to consider.

Userland knows that it can count on each Radio user being able to gain access to this same local IP on each of their personal computers. So, this IP serves as a wonderfully convenient 'location' for managing your local weblog while retaining the consistency of a browser-based interface and display model.

You could think of this IP as placing you at the center of the known universe:

(With thanks and a nod to the ThinkGeek folks).