Caveats: This guide was developed in order to troubleshoot DSL connections for the ISP where I work. It is used for Win9x and ME customers who use Verizon for the phone company portion of their connection, and we presume you have a static IP address (ie, no DHCP). The steps listed here should help you, but your mileage will definitely vary. Everything in this guide is presented at your own risk.

I've never been able to come up with a way to effectively troubleshoot a DSL connection for a Macintosh user, because of lack of built in commands like ping, arp, and so on. Which is part of why I'm contributing this information; I hope that someone will post an equivalent guide for Mac users. If you do, I'll send 10,000 fluffly pink Energizer bunnies to your doorstep.


  1. Power cycle the modem.
  2. Three solid green lights on the modem?
  3. Open DOS window and ping, ohhh,
    • If ping worked, goto step 10.
    • If ping failed, continue.
  4. Check for carrier light on the NIC.
  5. Click the Start button, then choose Run then type winipcfg. Check IP setup for NIC (not PPP).
    • If IP is good (it matches what your ISP told you to enter when you first got the account with them), note the IP number and continue.
    • If IP is bad, fix via the TCP/IP entry under "Network" from the Control Panel.
  6. Verify you have the correct gateway address for your IP address.
  7. Open a DOS window and ping your own IP address (from step 5).
  8. Ping gateway address
    • If ping failed, continue.
    • If ping worked, verify TCP/IP gateway settings.
  9. Open DOS window and enter command: arp -g
  10. Can you ping (as distinct from IP address given in step 3)?

I've omitted a couple of ISP-specific steps where they check entries in their router, but if you've gotten all the way to step 9 and haven't solved the problem, you'll need their help anyway.

You can download a freeware Macintosh program called WhatRoute, which will allow you to do ping, tracroute, nslookup, and other assorted tasks. The guide posted above is still pretty relevent for the Mac, and also relevant for any type of broadband connection. A couple Mac-specific things, though...

The equivalent of winipcfg on the Mac is the TCP/IP control panel. This will list your IP, netmask, gateway, and default DNS server. If the IP claims to be something beginning with 169, chances are you have some problems. Don't bother trying to ping, it won't work. One solution to this is to close TCP/IP, open the System Folder, open the Preferences Folder, and trash the file "TCP/IP Preferences". Immediately reboot your Mac and reconfigure your settings, then quit and save. This works surprisingly often. While it doesn't seem to be an issue with newer versions of Open Transport, it would sometimes happen that when you crashed, your preferences file would be corrupted, leaving your Mac unable to obtain an IP address.

And if you're using the wrong kind of twisted cable between your computer and your DSL/cable modem, it will never have worked at all. That's something you'll probably have to fix.

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