dog, the command-line DNS client

The OPT pseudo-record

The OPT (options) record is a pseudo-record that contains extra fields that were added to DNS later. If present, there should only be one of these in a DNS request or response.

dog sends OPT records as part of queries by defaults, but hides them in the response. For more information, see the EDNS section.


Here, we make a standard request to, but tell dog to show the OPT record in the response with the --edns option. It specifies a UDP packet size of 512, and is in the Additional section.

Because these records do not have a defined domain name or TTL, those values are left blank, and the data is shown in the final column instead.

$ dog --edns show
  A 1h00m00s
OPT                                + 512 0 0 0 []