RootCache: Filling Resolver Caches with Root Zone Records

Some DNS recursive resolver operators want to prevent snooping by third parties of requests sent to DNS root servers. Resolvers can reduce the number of queries sent to root server, and thus prevent observation of requests, by caching a copy of the full root zone. This document shows how a resolver can securely receive the full root zone and put it into the resolver's cache. This document obsoletes RFC 8806.