RFC 7043 / START HERE
DNS EUI records, before the details
EUI means Extended Unique Identifier; DNS means Domain Name System. RFC7043 defines EUI48 and EUI64 DNS records and is Informational, not an Internet Standard.
A DNS resource record stores a particular kind of data under a name. These two types store one supplied 48-bit or 64-bit link-layer address, such as an Ethernet identifier, in six or eight bytes. They report an address rather than proving who owns a device.
The idea in one picture
Choose the RR type
Encode the address
Restrict disclosure
A simplified picture of the idea; the chapters explain the actual mechanisms.
Why it exists
Private network-management systems may need a consistent way to exchange an EUI-to-IP mapping. The RFC defines exact binary and text encodings and describes a restricted-access cable-network example. It does not change ordinary IP address resolution or define a universal mapping schema.
A familiar example
A fictional private DNS view can provide a reseller with a modem’s example address and lease association. Publishing stable identifiers openly could enable tracking or MAC cloning; the RFC says these addresses SHOULD NOT be published in public DNS.
Helpful background
You can start here without reading another RFC. If these ideas are unfamiliar, these short introductions may help.
What you’ll learn next
Begin with chapter one, or choose a topic.
- Encode one EUI-48 address in six octetsEUI means Extended Unique Identifier. EUI48 is a DNS resource record containing one 48-bit link-layer address, such as an Ethernet address.→
- Keep an EUI-64 address as eight octetsEUI64 stores one 64-bit Extended Unique Identifier. It has its own DNS type and field length, rather than being an EUI48 record with optional extra bytes.→
- Separate presentation text from wire bytesA zone file is a human-readable DNS configuration. Its EUI address text uses fixed-width hexadecimal pairs, while the wire record contains binary octets.→
- Keep ordinary address resolution unchangedThese records carry address data to applications that choose to read them. Defining a new RR type does not rewrite existing address-resolution protocols.→
- Follow the private DOCSIS mapping exampleDOCSIS is a cable-network technology. The RFC’s example separates a cable operator that assigns an IP address from a reseller that already knows a modem’s EUI address.→
- Constrain tracking and address-cloning exposureA stable link-layer address can link changing IP addresses or names over time. Readable address data is not proof of a device’s identity or permission to track its user.→
This introduction explains RFC 7043 (2013). Read the original RFC ↗