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Re: [Ntp] Antw: Re: Antw: [EXT] Local time in NTPv5?

James <james.ietf@gmail.com> Sun, 31 July 2022 22:55 UTC

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From: James <james.ietf@gmail.com>
In-Reply-To: <a61f270a-837f-b1be-15e4-835cd50899cf@pdmconsulting.net>
Date: Mon, 01 Aug 2022 00:55:42 +0200
Cc: Hal Murray <halmurray@sonic.net>, Miroslav Lichvar <mlichvar@redhat.com>, "ntp@ietf.org" <ntp@ietf.org>
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To: Danny Mayer <mayer@pdmconsulting.net>
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Subject: Re: [Ntp] Antw: Re: Antw: [EXT] Local time in NTPv5?
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Danny,
It would be very much appreciated if you could dig out the RFC number or point to wherever DHCP specification, because I'm unable to find reference to anything that may hint, noting that the IANA registries for DHCP and DHCPv6 options, there is RFC 5908 mentioned which covers DHCPv6, but I am unable to find anything in reference to DHCPv4 - all that appears immediately obvious is Tag 4, which refers to RFC 2132, which in turn refers to the Time Protocol defined in RFC 868.

- J

> On 1 Aug 2022, at 00:27, Danny Mayer <mayer@pdmconsulting.net> wrote:
> 
> 
> On 7/29/22 12:27 PM, Hal Murray wrote:
>> mlichvar@redhat.com said:
>>> You mean the TZ POSIX string (option 100) from RFC4833? That looks like it
>>> could work, even for announcing the DST change.
>>> So, I guess the question is now are there any use cases for the local time in
>>> NTP without DHCP?
> That's irrelevant. NTP knows nothing about time zones.
>> That only works if the DHCP servers in use actually support it.
>> 
>> Is there a tool for poking at DHCP servers to see what they provide?  I poked
>> around a bit but diddn't find one.
>> 
>> I scanned the man page for the ISC DHCP server and didn't find any mention of
>> NTP or time zones.  (ntp was mentioned as a logging option.)
> 
> DHCP supports NTP server provisioning. I worked with the DHCP WG on it a number of years ago. I don't know the RFC number.
> 
> 
>> If a client gets its IP Address from a server, does it latch on to that server
>> and ignore others?  Or will it try broadcasting to find other servers before
>> giving up?  Can we setup a DHCP server that only provides time zone info?
>> 
> Read the DHCP RFCs. I don't know if there is provisioning for time zones.
> 
> Danny
> 
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