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 a complete recursive lookup, which always fetches a fresh result and therefore cannot distinguish a cached entry from an uncached one.

dnsnooping is not a recognized or installed command-line utility on standard operating systems.

The nslookup -norecursive flag instructs the DNS server not to perform a recursive resolution and to answer only from its local cache. If the record is returned the entry is cached, confirming prior resolution of that domain; if no answer is returned the domain was not recently queried, which reveals browsing or software update behavior without polluting the cache.

dns --snoop is not valid syntax for any standard DNS query tool.