The Messages by Opcode plot shows the breakdown of OPCODE values, other than QUERY, in DNS queries. Since QUERY is the most common opcode, its inclusion here would dominate the plot. Some of the less common opcodes are:

• IQUERY - An "inverse query" which has been deprecated in favor of the PTR query type.
• STATUS - A server status request.
• NOTIFY - Allows master servers to inform slave servers when a zone has changed.
• UPDATE - Add or delete RRs or RRsets from a zone.
• Other - All other opcode values, legitimate or not.

Click on the legend to view the queries for a specific opcode.