DNS Requests / Sec per IP

Attached this to your DNS listener

when CLIENT_DATA {
    table set -subtable [IP::client_addr] [TMM::cmp_unit][clock clicks] 0 1
    table set -subtable tracking [IP::client_addr] 0 5
}

Attached this to a HTTP virtual server with HTTP profile

when HTTP_REQUEST {
  if {[HTTP::uri] eq "/stats"} {
    set response ""
    foreach IP [table keys -subtable tracking] {
      append response "$IP Count [table keys -subtable tracking -count]\r\n"
    }
    HTTP::respond 200 content $response Content-Type "text/plain" Connection Close
  }
}

The first collects the statistics, the second allows you to see them from a virtual server.