Separate presentation text from wire bytes
03A zone file is a human-readable DNS configuration. Its EUI address text uses fixed-width hexadecimal pairs, while the wire record contains binary octets.
Separate colon-separated input 00:00:5e:00:53:2a does not match this RR’s required presentation syntax. The teaching reader stops before producing RDATA; this is not a claim about every tool’s accepted hardware-address syntax.
Source for this drawing: RFC 7043 · Read RFC section 3.2 ↗
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.
An EUI48 Address MUST be represented as six two-digit hexadecimal numbers separated by hyphens. EUI64 MUST use eight such pairs under §4.2.
- An EUI48 Address MUST be represented as six two-digit hexadecimal numbers separated by hyphens. EUI64 MUST use eight such pairs under §4.2.
- Hexadecimal A through F MAY be upper or lower case. Case changes the written form, not the encoded address.
- The complete RFC examples include TTL 86400 and class IN. Those chosen examples do not create a special TTL rule or limit either RR type to class IN.
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 ↗