Connectivity Troubleshooting (was Re: [ale] OT Speedfactory Problems Anyone?)

[James Baldwin]

On 27 Jan 2005, at 15:47, Bob Toxen wrote:

> Before tracerouting, I do:
>
>      ping -c 1 yahoo.com
>
> If it says "unknown host" or fails to output its first line with the
> DNS resolution that normally looks like:
>
>      PING yahoo.com (216.109.112.135) from 10.11.12.13 : 56(84) 
> bytes...
>
> then DNS is down.
>
> Regardless of that, know the IP of a system on the Internet and then
> do a traceroute to its numeric IP, e.g.,
>
>      traceroute 216.109.112.135
>
> You may want to give the "-n" flag to not do DNS resolution.

When checking for connectivity problems three great IPs to remember:
	4.2.2.2, 4.2.2.3 and 18.18.18.18

These are three DNS servers which will serve up responses to anyone, 
anywhere. I doubt that's what the provider intended, however it does 
make troubleshooting easy.

Any other tricks of the trade?
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