Read the generic text representation
03A master file is editable DNS zone text. TYPE followed immediately by a decimal number identifies a type; CLASS followed immediately by a decimal number identifies a class. The literal token \# introduces generic RDATA.
The official e.example. IN A \# 4 0A000001 example decodes to four bytes, 0A 00 00 01 (10.0.0.1). The server knows type A and MUST continue its normal A-specific processing; generic spelling does not erase type knowledge.
Source for this drawing: RFC 3597 · Read RFC section 5 ↗
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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.
After \#, an unsigned decimal octet count precedes zero or more hexadecimal words; every hex word has an even number of digits. Zero length is written \# 0.
- After \#, an unsigned decimal octet count precedes zero or more hexadecimal words; every hex word has an even number of digits. Zero length is written \# 0.
- The official example a.example. CLASS32 TYPE731 \# 6 abcd ( ef 01 23 45 ) represents AB CD EF 01 23 45. Parentheses group the multi-line master-file example; they are not RDATA bytes.
- Known types MAY use generic type, class and/or RDATA text. Further server processing MUST still apply known-type compression, canonicalization and other type-specific rules.
- The field reader used here accepts already-tokenized hex words only; it is not a complete zone lexer. A rejected length example is a local field error, not an invented DNS response code. RFC6895 reserves generic TYPE/CLASS-style names against allocation as ordinary mnemonics.
Offline bounded examples, not a complete DNS server, master-file parser or DNSSEC validator. Hexadecimal pairs represent octets (eight-bit bytes). Layouts are schematic unless marked otherwise. Generic data transport neither understands an application nor authenticates it.
Read the RFC section ↗