[ntp:questions] why do internet servers not poll atlonger intervals

David J Taylor david-taylor at blueyonder.co.uk.invalid
Wed Feb 15 09:20:27 UTC 2012

> My PC connects to my basement router with wifi G, which is then wired to 
> a wired router which is wired to the cable modem.  Service is Comcast 
> 16-20 Mbps down and 3-4 Mbps up.  I get pretty low jitter to the NY NIST 
> server, which is the one this machine normally hits if there is no GPS. 
> I'm not sure if Comcast has a public NTP server or not.
> Sincerely,
> Ron

So that's a Wi-Fi connection, plus a second router, Ron.  Not so direct. 
I'm still slightly surprised at the long delays, and wonder how heavily 
loaded with your own connection, or the lines provided by your ISP 
actually are.

I wonder about:

- making your basement box into an access point rather than router.  [I 
have that arrangement here, but I've never compared the delays or jitter 
comparing one approach to the other.]

- whether the cable modem or your own wired router can provide one 
additional NTP server?

Aside: I use DD-WRT on my own router, which does have an NTP client but 
not server.  I use that firmware as I can then use SNMP functions to 
interrogate the router and plot the results with MRTG:


Some router parameters:

Apparently, Comcast did have some NTP servers back in 2006:


The router next upstream, or next but one, from your premises may be worth 
checking for NTP.  Sometimes these devices will provide an NTP service 
even though they don't response to and "ntpq -p".  I would just add one to 
your existing configuration to see how good or otherwise it is.


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