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.

Example

Here, we make a standard request to a-example.lookup.dog, 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 a-example.lookup.dog --edns show
  A a-example.lookup.dog. 1h00m00s   10.20.30.40
OPT                                + 512 0 0 0 []