DNS Troubleshooting

Symptoms:
- Name lookups fail for names you know are good
- The network is working (you can ping addresses on the Internet)
Use nslookup, host, or dig to find out which nameserver is broke
If all fail it is probably your nameserver
If one domain fails it is probably their nameserver or their delegation

How do you tell it is DNS failing? "Unknown host," "name could not be found", etc.

Internet Explorer is particularly unhelpful–large error page with 2 lines at the bottom: "Cannot find server or DNS Error" Other programs can be worse.

If you can't get to your nameserver or to the Internet it is a network problem, try other tools (e.g., traceroute). Ping is good at differentiating.