[ntp:questions] Meinberg NTP Software--Time Accuracy

Danny Mayer mayer at ntp.org
Sun Jun 28 01:24:14 UTC 2009

Todd Glassey CISM CIFI wrote:
> Danny Mayer wrote:
>> tglassey wrote:
>>> Danny Mayer wrote:
>>>>>>> By geography, just like the zones that were mentioned in the post
>>>>>>> above.
>>>>>>> However, they are more fine-grained, especially when compared with
>>>>>>> large zones like us or eu.
>>>>>> How are you going to know the geography. DNS clients does not supply
>>>>>> that information even if they knew it and it's certainly not part of
>>>>>> the
>>>>>> DNS protocol.
>>>>> Danny isnt the location data potentially available as part of HOST
>>>>> listings and Location Records?
>>>> What Host listings and Location Records? There are no such types
>>>> available in DNS and even if they were they would not be local to the
>>>> nameserver responding. In any case such records would be entirely
>>>> voluntary, ie never added to a nameserver anywhere.
>>> Ah, let me be clearer -  I didn't say lots of people were using it, and
>>> it is as well as defining Well Known Services. As it happens though
>>> there are some folks who do use these. Especially true with some of the
>>> military BF (battle field)  process equipment.
>> This makes no sense. The are no such types and so they cannot be used
>> even if they existed. Furthermore the only entry in the request is the
>> name for which an address is requested. The client does not even send
>> the request directly to the authoritative server. It makes a request via
>> a resolving server and that is the server that contacts the
>> authoritative server. The authoritative server has no knowledge
>> whatsoever not only of the client but what it intends to do with the
>> returned addresses.
> Right - explain that to Vix will ya? - http://tools.ietf.org/html/rfc1876

The LOC RR is almost universal in being an ignored RR. The are so few
people populating it that it may as well not exist.

>> As for Well Known Services I assume you are talking about SRV records
> You mean RFC2782 specfied SRV records - sure they work but so do the
> legacy Location Records and the WKS1035) can have this data in them as
> well.

I don't remember the last time I saw a usage of WKS. I believe that MIT
may use it, but in HS (Hesiod) and not IN (Internet).

>> but those don't even come into the picture here. BF process equipment
>> don't use DNS for this kind of stuff. 
> Here is one of many papers on location specific information in DNS -
> https://www.cs.tcd.ie/~htewari/papers/acts99.pdf

Yes and it relies on DNS dynamic updates to the zone. Since so few DNS
allow dynamic updates to their zones this is so limited as to be
useless. BF equipment use the military version of GPS and the
information is not stored in DNS but in highly secure systems.


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