The source of any Internet audio broadcast can be determined with an Internet Protocol (IP) address lookup tool. Audio sources are identified in most cases with a domain name, which is resolved to an IP address automatically by your computer with a Domain Name Server (DNS) lookup. When you need to obtain the numerical address of an audio server, you can do so by accessing DNS data manually.
Hover over an audio link on the web, without clicking on it. The address for the audio stream should appear in the browser, usually in an information banner in the bottom of the window.
Right-click or control-click on the link to bring up the contextual menu. Choose the copy command to copy the URL.
Paste the URL into any text editor (such as Windows Notepad or Mac TextEdit). Select only the domain name from the URL, which appears between "http://" and the first "/" character afterwards. (For some audio URLs, the beginning of the URL won't be "http". Select starting after the "//" regardless.) Copy the domain name to the clipboard.
Open a DOS window on Windows, which is available in the Start menu. On Macintosh, open a Terminal window by double-clicking on the Terminal application in /Applications/Utilities.
Type "nslookup", one space, and paste the domain name you copied in step 3. The IP address will be returned to you.