On 21 Feb 2019, at 14:34, Mark Andrews <[email protected]> wrote:

> Machines die. Machines are unplugged.  Server are unreachable at critical 
> times. Externally driven cleanup can never be reliable. 

I'm not disputing any of that. I guess my first question was first whether 
cleanup is necessary, and second (assuming it is) whether cleanup can't just be 
handled as an implementation detail as opposed to a protocol extension.

If the master server that receive UPDATEs matching particular names could be 
configured to remove them after a suitable interval, wouldn't that do the 
trick? Slave servers would get new copies of the zones concerned following the 
updates in the normal manner. Zone propagation is pretty swift with NOTIFY. The 
master could apply policy based on criteria like owner name pattern matching or 
source of the update. Garbage collection might not happen with the kind of 
split-second accuracy that I sense this mechanism's proponents are suggesting, 
but does it need to? Don't we believe that applications that expect more than 
loose coherence from the DNS are broken?

I hear and acknowledge there is a desire for this kind functionality (i.e. I 
believe you that it's necessary) but I'm still not clear on what need there is 
for interoperability (and hence standardisation). Every DNS implementation 
contains their own special features that are not standardised and that don't 
need to be. Couldn't this be another one?

I remain open to the idea that I am just missing the point because I don't 
spend enough time in enterprise or campus networks. I think I'm possibly not 
the only one in that boat, though, and I don't think it's unreasonable for the 
draft to explore its applicability and explain clearly why standardisation or 
in-zone signalling (hence RRs) is necessary as a prerequisite to 
standardisation. As I mentioned before, the bar for experimental is surely much 
lower, and the bar for simple codepoint assignment lower still.


Joe
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