Expand description
Extended DNS RFC6891
EDNS adds information to DNS messages in the form of pseudo-Resource Records (“pseudo-RR“s) included in the “additional data” section of a DNS message. This takes the form of an OPT RR which contains a UDP payload size the server supports, an EDNS version number, flags, an extended RCode, and possibly a variable number of KVP options. Most notably this allows servers to advertise that they can process UDP messages of size > 512 bytes (the default maximum for DNS over UDP).