Authoritative Resources for Public DNS Pinging

Sat Feb 12 09:17:26 UTC 2022

On 2/11/22 16:58, Jon Lewis wrote:

>
> I have to admit, I haven't read most of this thread, but I am well 
> aware of the issues with both end users and "routers" / firewalls 
> pinging 8.8.8.8 as a means of verifying "that path to the Internet is 
> working".  I know GOOG doesn't appreciate the amount of ICMP echo 
> requests their 8.8.8.8 instances receive, and that at various 
> times/places, that ICMP traffic is/has been policed by GOOG.
>
> So...here's a pair of "what if"s:
>
> What if instead of pinging 8.8.8.8, all these things using it to "test 
> the Internet" sent it DNS requests instead?  i.e.
> GOOG=$(dig +short @8.8.8.8 google.com)
> if [ -z "$GOOG" ] ; then
>   echo FAIL
> fi Would that make things better or worse for GOOG (Trading lots more 
> DNS requests for the ICMP echo requests)?

Could work for devices, but more difficult for Jane.

>
> 8.8.8.8 is already anycasted.  What if each large ISP (for whatever 
> definition of large floats your boat) setup their own internal 
> instance(s) of 8.8.8.8 with a caching DNS server listening, and 
> handled the traffic without bothering GOOG?  For users using 8.8.8.8 
> as a lighthouse, this would change the meaning of their test...i.e. a 
> response means their connection to their ISP is up, and the ISP's 
> network works at least enough to reach an internal 8.8.8.8, but the 
> question of their connectivity to the rest of the Internet would be 
> unanswered.

Something tells me Google (or Cloudflare, or Quad9, or e.t.c.) would not 
consider that a good thing, for them :-).

Mark.