Encode one EUI-48 address in six octets
01EUI means Extended Unique Identifier. EUI48 is a DNS resource record containing one 48-bit link-layer address, such as an Ethernet address.
Separate fixture supplies only five address octets for EUI48. The reader refuses to interpret it as the required six-octet field. This illustrates a format mismatch, not an RFC-defined DNS error reply.
Source for this drawing: RFC 7043 · Read RFC section 3.1 ↗
New to this? Start hereA quick picture + helpful background
A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
Helpful first, if these ideas are unfamiliar
These pictures are analogies to help you learn. The linked RFC explains the actual rules.
Terms in this drawing
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
EUI48 has decimal DNS type 108. Its RDATA is a single six-octet Address field in network, or big-endian, order.
- EUI48 has decimal DNS type 108. Its RDATA is a single six-octet Address field in network, or big-endian, order.
- DNS owner name, type, class, TTL and RDLENGTH are outside this Address field. Hyphens in presentation text are not wire octets.
- An octet is eight bits: six octets hold 48 bits. The published example is pedagogical here; no real interface or subscriber is queried.
Fictional offline examples only. EUI records carry supplied address data; they do not authenticate devices, implement IP resolution or authorize tracking. RFC7043 is Informational. The application policies shown are explicitly chosen fixtures.
Read the RFC section ↗