Re: LLMNR Issue 58: DNS server usage of LLMNR

[Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>]

Bernard Aboba;

> > 	LLMNR is expected to be useful for nodes on an isolated
> > 	IP network with a single link, but not beyond that. LLMNR
> > 	MUST NOT be used by nodes connected to the Internet nor
> > 	an isolated IP network with multiple links.

> Whether the network is "isolated" or "connected to the Internet" is
> very hard to determine.  A host may be able to reach some Internet
> prefixes, and not be able to reach others.  Similarly, the radius of the
> network may also be hard to determine.

It is trivially easy for an administrator of the network.

> LLMNR use is restricted to situations in which DNS servers are not
> configured, where DNS servers do not respond or where
> DNS responds with RCODE=3 or RCODE=0 and no RRs.

The problem is that, LLMNR is still not useful unless the network
is an isolated single link that LLMNR should never be attempted
otherwise.

> However, the host is not obliged to dig deeper to  understand *why* these
> situations occur,

Agreed, but it is not my point.

Given the difficulty you mentioned, I think it is also necessary
to request that LLMNR functionality is, by default, turned off.

						Masataka Ohta



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