name resolution

Tom H tomh0665 at gmail.com
Fri Nov 24 09:03:21 UTC 2017


On Fri, Nov 24, 2017 at 1:26 AM, Xen <list at xenhideout.nl> wrote:
> Tom H schreef op 23-11-2017 22:32:
>> On Thu, Nov 23, 2017 at 1:58 PM, Xen <list at xenhideout.nl> wrote:


>>> I just think it's another bad choice and it happens to have been
>>> pushed by mr. SystemD himself.
>>>
>>> Yes, Lennart Poettering also maintains the Avahi packages.
>>>
>>> It's the same kind of "Your opinions don't matter" approach that we
>>> see everywhere else.
>>>
>>> He writes:
>>>
>>> " Please note: The line above makes nss-mdns authoritative for the
>>> .local domain. If you have a unicast DNS domain with the same name
>>> you will no longer be able to resolve hosts from it. mDNS and a
>>> unicast DNS domain named .local are inherently incompatible. Please
>>> contact your local admistrator and ask him to move to a different
>>> domain name since .local is to be used exclusively for Zeroconf
>>> technology. [26]Further information."
>>>
>>> "is to be used"
>>>
>>> Because they decide that.
>>>
>>> This encroachment on personal liberty goes on everywhere.
>>
>> It was an Apple decision not Lennart one.
>
> Apple didn't decide for the rest of the world.

It did.

It used SLP for zero config networking in pre OS X releases and in OS
X 10.0 and 10.1.

It started using Rendezvous for zero config networking in OS X 10.2,
renamed it Bonjour in OS X 10.5, and has been using it ever since.

Lennart re-implemented Bonjour, I've forgotten when, as a gpl-licensed
technology for use in Linux and BSD.


> There is no reason whatsoever that mDNS has to precede DNS.
>
> The only "reason" for that is to prevent leakage onto the internet, which
> are queries to the root domain for .local, which returns NULL.
>
> At every stage, this can be blocked by DNS servers, and probably is.
>
> If you put mDNS AFTER dns, it will still work, and not frustrate operation
> of the DNS system.
>
> The delay in first accessing the global DNS system and only then mDNS is
> minimal.
>
> The reverse is not true; mDNS has a timeout of about 4 seconds or nearing
> that.
>
> So by all extents and purposes, you should put mDNS AFTER DNS, unless of
> course

In your use-case, perhaps.

In the general use-case, all distributions have chosen the logical
choice of querying mdns before dns.


> YOU WANT TO EXTINGUISH THE USE OF THE LOCAL DOMAIN BY FORCIBLE MEASURES.
>
> Which they are doing.
>
> Not practical necessity.
>
> Politics.

Of course, practical necessity. You can plug a laptop into a network
and see all the network shares immediately, whether they're files or
printers (whether you can then access them is a different matter).
That's the meaning of "zeroconf."




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