How can dhclient request a prefix delegation of a specific length from provider?

Thomas Markwalder tmark at
Tue Oct 4 11:01:22 UTC 2016

On 10/3/16 5:47 PM, John Ioannidis wrote:
> On Mon, Oct 3, 2016 at 2:54 PM, Mike <the.lists at> wrote:
>> On 10/1/2016 5:38 PM, John Ioannidis wrote:
>>> If I specify the -P option, my provider dutifully delegates me a /64.
>>> It will, however, delegate me a /56 if I ask for one. How do I specify
>>> the length of the prefix I want delegated?
>>> If it's documented somewhere, I can't find it :(
>> Here's a thread that you may find helpful...
> Thanks (and to others who responded before).
> is a
> summary of what I did.
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> dhcp-users mailing list
> dhcp-users at

Hello John:

We are looking to address this issue in our next major release, ISC_DHCP
4.4.0.  Development on this release is underway, although we do not yet
a have a release time frame for it.   We will certainly take your
solution into consideration and would like to commend you for your
efforts.   In order to ensure you stay apprised of what we do with this
issue it would help considerably if you could report the issue as a bug


Thomas Markwalder

ISC Software Engineering

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