[dns-operations] cache and subnet option

[Randy Bush]

dear lazynet,

caching resolver R serves clients on subnets S0 and S1.  a device on S0
queries for wanna.know.  R queries for the data using the subnet option.
a device on S1 then queries for wanna.know.  does R respond with the
cached data from the S0 query, or issue a new query with the S1 subnet
data?

[ to my naïve eye, issuing a second query would seem to have, shall we
  say, interesting scaling properties ]

randy