Re: [dhcwg] Network Time Protocol (NTP) Options for DHCPv6

Mark Stapp <mjs@cisco.com> Wed, 28 November 2007 22:29 UTC

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Date: Wed, 28 Nov 2007 17:29:16 -0500
From: Mark Stapp <mjs@cisco.com>
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To: Bud Millwood <budm@weird-solutions.com>
Subject: Re: [dhcwg] Network Time Protocol (NTP) Options for DHCPv6
References: <A05118C6DF9320488C77F3D5459B17B7062ED3C6@xmb-ams-333.emea.cisco.com> <200711282235.17331.budm@weird-solutions.com>
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the suggestion's out there that it might be better if the option allowed 
for lists of addresses or names - or both. there do seem to be valid 
cases for both kinds of data: DNS names for load-balancing or use of the 
'pool', addresses for situations where a resolver may not be available.

-- Mark

Bud Millwood wrote:
> How many DHCP options are normally configured to point to services outside of 
> the operator's domain? How many public SIP servers are there, for example?
> 
> As a server writer I have a built-in aversion to changing the way we 
> distribute location of services, but in this case it seems justified to use a 
> DNS name simply because the de-facto standard, as far as I can tell, is to 
> point clients outside the admin-controlled domain. So maybe the projected use 
> of the service has a real bearing on this discussion.
> 
> I've read this thread a little quickly, but it seems that we could end up 
> passing multiple NTP server IP addresses to DHCP clients. If so, then the 
> packet space argument against DNS names starts to break down the more 
> addreses you distribute. At some point it would be less space to send the DNS 
> name than a list of n addresses.
> 
> And as for the argument that a DNS name requires a resolver on the client: how 
> big of an issue is this, really? How many devices are really likely to want 
> to sync their clocks over NTP but not have even a rudimentary resolver?
> 
> - Bud
> 
> Bud Millwood
> Weird Solutions, Inc.
> http://www.weird-solutions.com
> tel: +46 8 758 3700
> fax: +46 8 758 3687
> 
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