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| NAMED-RRCHECKER(1) | BIND 9 | NAMED-RRCHECKER(1) |
NAME
named-rrchecker - syntax checker for individual DNS resource records
SYNOPSIS
named-rrchecker [-h] [-o origin] [-p] [-u] [-C] [-T] [-P]
DESCRIPTION
named-rrchecker reads a single DNS resource record (RR) from standard input and checks whether it is syntactically correct.
- Input must not start with an owner (domain) name
- The CLASS field is mandatory (typically IN).
- The TTL field must not be present.
- RDATA format is specific to each RRTYPE.
- Leading and trailing whitespace in each field is ignored.
Format details can be found in RFC 1035 Section 5.1 under <rr> specification. RFC 3597 format is also accepted in any of the input fields. See Examples.
OPTIONS
- -o origin
- This option specifies the origin to be used when interpreting names in the record: it defaults to root (.). The specified origin is always taken as an absolute name.
- -p
- This option prints out the resulting record in canonical form. If there is no canonical form defined, the record is printed in RFC 3597 unknown record format.
- -u
- This option prints out the resulting record in RFC 3597 unknown record format.
- -C, -T, -P
- These options do not read input. They print out known classes, standard types, and private type mnemonics. Each item is printed on a separate line. The resulting list of private types may be empty
- -h
- This option prints out the help menu.
EXAMPLES
Pay close attention to the echo command line options -e and -n, as they affect whitespace in the input to named-rrchecker.
- Valid input is in RFC 1035 format with no newline at the end of the input.
- Return code 0.
- Valid input with leading and trailing whitespace.
- Output: IN A 192.0.2.1
- Leading and trailing whitespace is not part of the output.
Relative names and origin
- Valid input with a relative name as the CNAME target.
- Output: IN CNAME target.
- Relative name target from the input is converted to an absolute name using the default origin . (root).
- Valid input with a relative name as the CNAME target.
- Output: IN CNAME target.origin.test.
- Relative name target from the input is converted to an absolute name using the specified origin origin.test
- Valid input with an absolute name as the CNAME target.
- Output: IN CNAME target.
- The specified origin has no influence if target from the input is already absolute.
Special characters
Special characters allowed in zone files by RFC 1035 Section 5.1 are accepted.
- Valid input with backslash escapes.
- Output: IN CNAME target\..origin.test.
- \097 denotes an ASCII value in decimal, which, in this example, is the character a.
- \g is converted to a plain g because the g character does not have a special meaning and so the \ prefix does nothing in this case.
- \. denotes a literal ASCII dot (here as a part of the CNAME target name). Special meaning of . as the DNS label separator was disabled by the preceding \ prefix.
- Valid input with @ used as a reference to the specified origin.
- Output: IN CNAME origin.test.
- Valid input with a literal @ character (escaped).
- Output: IN CNAME \@.origin.test.
- Valid input with @ used as a reference to the specifed origin.
- Output: IN CNAME prefix.\@.origin.test.
- @ has special meaning only if it is free-standing.
- Valid input with a trailing comment. Note the lack of whitespace before the start of the comment.
- Output: IN A 192.0.2.1
For multi-line examples see the next section.
Multi-token records
- Valid TXT RR with two unquoted words and trailing whitespace.
- Output: IN TXT "two" "words"
- Two unquoted words in the input are treated as two <character-string>s per RFC 1035 Section 3.3.14.
- Trailing whitespace is omitted from the last <character-string>.
- Valid TXT RR with one character-string and trailing whitespace.
- Output: IN TXT "two words"
- •
- Invalid input - the closing " is not detected before the end of the line.
- Valid input with an escaped newline character inside character-string.
- Output: IN TXT "with newline\010"
- Valid multi-line input with line continuation allowed inside optional parentheses in the RDATA field.
- Output: IN TXT "two" "words"
- •
- Invalid input - comments, starting with ";", are ignored by the parser, so the closing parenthesis should be before the semicolon.
- Valid input - the comment is terminated with a newline.
- Output: IN TXT "two" "words"
- Valid HTTPS record
- Output: IN HTTPS 1 . alpn="h2,h3"
- Valid HTTPS record with individual sub-fields split across multiple lines using RFC 1035 Section 5.1 parentheses syntax to group data that crosses a line boundary.
- Note the missing whitespace between the closing parenthesis and adjacent tokens.
- Output: IN HTTPS 1 . alpn="dot" port=853
Unknown type handling
- Valid input in RFC 1035 format.
- Output in RFC 3957 format: CLASS1 TYPE1 \# 4 C0000201
- Valid input in RFC 3597 format.
- Output in RFC 1035 format: IN A 192.0.2.1
- Valid input with class and type in RFC 1035 format and rdata in RFC 3597 format.
- Output in RFC 1035 format: IN A 192.0.2.1
- Valid input with RFC 9460 syntax for an unknown key3 field. Syntax \001\000 produces two octets with values 1 and 0, respectively.
- Output: IN HTTPS 1 . port=256
- key3 matches the standardized key name port.
- Octets 1 and 0 were decoded as integer values in big-endian encoding.
- •
- Invalid input - the length of the value for key3 (i.e. port) does not match the known standard format for that parameter in the SVCB RRTYPE.
- •
- Invalid input - the key port, when specified using its standard mnemonic name, must use standard key-specific syntax.
Meta values
- •
- Invalid input - AXFR is a meta type, not a genuine RRTYPE.
- •
- Invalid input - ANY is meta class, not a true class.
- •
- Invalid input - the class field is missing, so the parser would try and fail to interpret the RRTYPE A as the class.
RETURN CODES
- 0
- The whole input was parsed as one syntactically valid resource record.
- 1
- The input is not a syntactically valid resource record, or the given type is not supported, or either/both class and type are meta-values, which should not appear in zone files.
SEE ALSO
RFC 1034, RFC 1035, RFC 3957, named(8).
AUTHOR
Internet Systems Consortium
COPYRIGHT
2025, Internet Systems Consortium
| 2025-07-04 | 9.20.11 |
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