Master/slave configuration

[Niall O'Reilly]

On 08/03/12 11:58, Glenn Satchell wrote:
> On 03/08/12 20:22, Niall O'Reilly wrote:
>>
>> On 8 Mar 2012, at 02:58, Lyle Giese wrote (on bind-users):
>>
>>> On linux boxes, adding
>>>
>>> options rotate
>>>
>>> to the /etc/resolv.conf helps.
>>
>> [cross-posted, reply-to header set]
>>
>> Is there a DHCP option which expresses that, and which
>> typical fielded DHCP clients will respect?
>>
>> As you may guess, I don't have access to those thousands
>> of client systems out there.
>>
>> /Niall
>>
> Sorry Niall, but I think we need a little more context here to know what
> you are asking about. Something to do with /etc/resolv.conf or name
> servers?

	My mistake: I'm sorry.  I see what you mean, Glenn.

	There was a thread on bind-users discussing the problem of
	delayed DNS service which arises when the first name server
	configured in /etc/resolv.conf becomes unreachable and clients
	doggedly keep on trying it before any of the other for each
	new DNS query.

	Lyle Giese (see extract above) suggested specifying
	"options rotate" in /etc/resolv.conf as mitigation.

	This is fine if access to the client configuration is available.

	Many thousands of client systems on the network I help
	support derive the content of /etc/resolv.conf (or equivalent)
	from interacting with our DHCP servers.  We don't have any
	other effective access to the client units.

	I'm not aware of a DHCP option which is intended to allow a
	client to set "options rotate" or equivalent.  I'm also not
	aware of whether such an option, if it exists, is sufficiently
	widely respected in real-world fielded DHCP clients in their
	default configuration as to be worth considering.

	I'm asking to have those gaps in my awareness filled in.
	The answer I'm expecting is, "No.  No.  Forget it."
	I could be wrong; it wouldn't be the first time.  8-)

	Please everyone, accept my apologies for causing confusion
	by not providing enough context before.

	Thanks to Glenn for taking the trouble to point out my
	mistake.


	Best regards,
	Niall O'Reilly