DNS cache snooping is a process of determining if the specified resource address is present in the DNS cache records. It may be useful during the examination of the network to determine what software

The `-fullrecursive` flag forces the DNS server to perform a full recursive resolution, which always retrieves the record and therefore cannot distinguish between a cached and uncached entry.

`dnsnooping` is not a valid or recognized command-line utility on any standard operating system.

The `-norecursive` flag instructs the DNS server not to perform a new recursive lookup. If the record is present in cache, the server returns it; if absent, it returns nothing. This behavior is the foundation of cache snooping - a recursive query would always fetch the record, making it impossible to determine whether it was cached beforehand.

`dns --snoop` is not a real command and does not exist in any standard DNS toolset.