[ntpwg] [dhcwg] Re: Network Time Protocol (NTP) Optionsfor DHCPv6

[Danny Mayer]

Mark Andrews wrote:
>> On Nov 25, 2007, at 3:24 PM, Brian Utterback wrote:
>>> If a client is served an IP address at start up time, it has no  
>>> choice but to use that address for the
>>> entire time it is up and running.
>> This is simply not true.   The client would get the currently- 
>> configured NTP server IP address every time it renews its lease.    
>> It's true that some NTP clients may not bother to check their  
>> configuration information for updates, but it is not true that they  
>> have no choice - checking for configuration updates is trivial.
>>
>> Indeed, I would say that at this late date, a network service that  
>> gets its configuration information from the DHCP client, but does not  
>> follow updates to that information, is broken.  Information provided  
>> by the local DHCP server will most likely change when the client moves  
>> from network to network.   The information that worked on one network  
>> may not work at all on another.   This is true whether the information  
>> is a domain name or an IP address.
> 
> I would think that this should be a push operation from the dhcp
> client rather than a pull operation.  A trivial push would be for
> the DHCP client to re-start the NTP client on address change (NTP
> server and optionally lease address change).
> 
> I already do the later as the NTP client doesn't notice lease address
> changes.
> 
> Mark

You must be running an old NTP server. As of 4.2.4 ntpd rescans the
interfaces for local interface address changes. You can disable
rescanning by using -U 0 on the startup command line.

Danny