From the BIND 9 Administators Reference Manual (doc/arm).
The description of the "queries" channel.
Specify where queries should be logged to.
At startup, specifing the category queries will also enable query logging unless querylog option has been specified.
The query log entry reports the client's IP address and port number. The query name, class and type. It also reports whether the Recursion Desired flag was set (+ if set, - if not set), EDNS was in use (E) or if the query was signed (S).
client 127.0.0.1#62536: query: www.example.com IN AAAA +SE
client ::1#62537: query: www.example.net IN AAAA -SE
From boolean options.
Specify whether query logging should be started when named start. If querylog is not specified then the query logging is determined by the presence of the logging category queries.