[ntp:questions] http://www.ntp.org/ => a blank page?

David J Taylor david-taylor at blueyonder.neither-this-bit.nor-this.co.uk
Tue Mar 10 10:07:11 UTC 2009

Martin Burnicki wrote:
> David,
> David J Taylor wrote:
>> Richard B. Gilbert wrote:
>> []
>>> I've been using Comcast for five or six years now without a problem!
>>> YMMV.
>> There have been a few problems with my ISP, hence I moved to a 3rd
>> party.
> We did't ever have any problems using the DNS servers of our ISPs.

At the time, mine was using servers in the USA (from the UK) and via 
non-reciprocal paths.  Even now, it seems to be using servers from abroad, 
and has no local reference clock....  I don't think that anyone "cared" 
for it.

>> I used to have my own DNS server.  You do /not/ have to get the rest
>> of the world from Comcast.  DNS is /not/ like NTP, and you talk
>> directly to the root servers to start with, which then pass you down
>> gradually to the correct server for the domain (e.g. for
>> microsoft.com) and in future you query the relevant domain server
>> directly.  All seems to work very smoothly and automatically.
> IMHO DNS is not like NTP in the sense that is just *starts* sending
> queries for domains which have not yet been resolved to the root DNS
> servers and then are redirected/go on down to the authoritative DNS
> for that domain, whereas NTP would stuck with the top level servers
> if they have been configured.

Agreed.  When I first answered I had missed that Richard probably knows 
more about DNS than me!

> However, if several local subnets needed to resolve "microsoft.com"
> then each one would have to ask the root servers the first time.

Wouldn't you have one or two central DNS servers for both subnets?

> If you send DNS queries to your ISP's servers then this would save
> bandwidth since they are normally closer to your network than the
> root DNS servers, and there is a chance that other customers of your
> ISP has already sent queries for "microsoft.com" so this has already
> been cached by the ISP's DNS servers and no request has to be made to
> the root servers.
> IMHO in this sense it's similar to NTP so the load is distributed and
> not concentrated on the root servers.
> Martin

Agreed, it's a distributed system.  I monitor the faults reported to my 
ISP, and DNS problems do come up, hence my preference for a 3rd party 
solution.  It's also one less thing to change were I to change ISP.


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