When I run the following dig command on www.google.com with the +nssearch option I get no results:
mac$ dig www.google.com +nssearch
mac$
Can someone explain why no data is returned here? The +nssearch option reads the SOA of all the authoritative name servers I believe. Does this mean there are no authoritative name servers? How is that possible? The domain www.google.com obviously works so I was expecting some sort of result.
www.google.com is not a zone, but a name in a zone. Therefore it doesn't have any NS records (or SOA records) for dig to display. Try dropping the www. bit and you'll get more output.