🚀 go-pugleaf

In article 
<barmar-F56611.00213018072010@62-183-169-81.bb.dnainternet.fi>,
 Barry Margolin <barmar@alum.mit.edu> wrote:

> 
> The Mac can only tell whether its WiFi connection to the AEBS is up.  
> 
> You can go to 192.168.100.1 to see the status of the modem.  If you can 
> get to this address, then the Mac and AEBS are fine.
> 

Barry, I don't know what you mean by "The Mac can only tell whether its 
WiFi connection to the AEBS is up".

Sitting at the Mac keyboard, I can open System Prefs, Network pane, and 
with a few steps (like clicking on an "Assist me" button), bring up a 
window titled "Network Diagnostics".  

Down the left column of that window, which is headed "Network Status", 
are 6 colored indicators (they look very much like radio buttons, but 
aren't) that can turn green, yellow, or red, and that are labeled from 
top to bottom as "Airport", "Airport Settings", Network Settings", 
"ISP", "Internet", and "Server".

At the minute I have 6 greens, and all is well.  When Comcast is down, I 
get 4 greens and the final two are yellow or red.  Sure seems to me my 
Mac (or at least my Mac + AEBS combo) is able to tell me, via the final 
two (or three) of those lights something about the status of stuff 
that's physically located miles from my desk.

In any case, I'd like to learn:

1)  Where or what is the "Network Diagnostics" software that creates 
this window labeled "Network Diagnostics"?  (Cmd-clicking on its title 
doesn't take me anywhere, and I don't find any app or utility with that 
name on my HD; is it some internal part of the Network prefs panel?)

2)  What do those colored light mean? (esp. the three bottom ones).

3)  Where else can I go for info on this? (besides the Genius Bar at the 
local Apple Store).