Asking for early review to avoid late surprises...
Please focus on if this might break existing deployments, etc.
This is currently in DNSOP, and is almost cooked -- the summary is
that asking a stub resolver for "localhost" will return 127.0.0.1 /
::1, but asking the DNS will return NXDOMAIN (it is an error to ask
the DNS this question, DNSSEC would have weird failure modes if we
tried to override it, etc) -- this document largely codifies existing
behavior.
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Abstract:
... To that end, stub resolvers are required to
resolve localhost names to loopback addresses. Recursive DNS servers
are required to return "NXDOMAIN" when queried for localhost names,
making non-conformant stub resolvers more likely to fail and produce
problem reports that result in updates.
Together, these requirements would allow applications and
specifications to join regular users in drawing the common-sense
conclusions that "localhost" means "localhost", and doesn't resolve
to somewhere else on the network.
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