Use one of the numerous dynamic IP DNS services such as http://www.dyndns.com

It's free and gives you a proper host name you can use.  You either need to run a service on your computer to update the database, or quite a few broadband routers have the facility built in.

Regards

Mike

>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 11 September 2006 10:38
>To: Microcontroller discussion list - Public.
>Subject: [EE] detecting if Computer with dynamic ip is on-line
>
>
>
>when using fixed ip, i can use ping to check if a computer is 
>up and running. if i have dynamic ip, i cannot do this as i do 
>not know the actual ip. is there a way to do something like 
>ping, but directly going to the mac address instead of the ip? 
>thanx! tino
>
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