Name Server Operations Guide for BIND Release 4.9.5 : Files : Standard Resource Record Format
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6.5. Standard Resource Record Format

The records in the name server data files are called resource records. The Standard Resource Record Format (RR) is specified in RFC1035. The following is a general description of these records:

{name}	 {ttl}	 addr-class   Record Type   Record Specific data
Resource records have a standard format shown above. The first field is always the name of the domain record and it must always start in column 1. For all RR's other than the first in a file, the name may be left blank; in that case it takes on the name of the previous RR. The second field is an optional time to live field. This specifies how long this data will be stored in the data base. By leaving this field blank the default time to live is specified in the Start Of Authority resource record (see below). The third field is the address class; currently, only one class is supported: IN for internet addresses and other internet information. Limited support is included for the HS class, which is for MIT/Athena ``Hesiod'' information. The fourth field states the type of the resource record. The fields after that are dependent on the type of the RR. Case is preserved in names and data fields when loaded into the name server. All comparisons and lookups in the name server data base are case insensitive. The following characters have special meanings:

``.'' A free standing dot in the name field refers to the root domain. ``@'' A free standing @ in the name field denotes the current origin. ``\eX'' Where X is any character other than a digit (0-9), quotes that character so that its special meaning does not apply. For example, ``\e.'' can be used to place a dot character in a label. ``\eDDD'' Where each D is a digit, is the octet corresponding to the decimal number described by DDD. The resulting octet is assumed to be text and is not checked for special meaning. ``( )'' Parentheses are used to group data that crosses a line. In effect, line terminations are not recognized within parentheses. (At present, this notation only works for SOA RR's and is not optional.) ``;'' Semicolon starts a comment; the remainder of the line is ignored. Note that a completely blank line is also considered a comment, and ignored. ``*'' An asterisk signifies wildcarding. Note that this is just another data character whose special meaning comes about only during internal name server search operations. Wildcarding is only meaningful for some RR types (notably MX), and then only in the name field -- not in the data fields.

Anywhere a name appears -- either in the name field or in some data field defined to contain names -- the current origin will be appended if the name does not end in a ``.''. This is useful for appending the current domain name to the data, such as machine names, but may cause problems where you do not want this to happen. A good rule of thumb is that, if the name is not in the domain for which you are creating the data file, end the name with a ``.''.

6.5.1. $INCLUDE

6.5.2. $ORIGIN

6.5.3. SOA - Start Of Authority

6.5.4. NS - Name Server

6.5.5. A - Address

6.5.6. HINFO - Host Information

6.5.7. WKS - Well Known Services

6.5.8. CNAME - Canonical Name

6.5.9. PTR - Domain Name Pointer

6.5.10. MX - Mail Exchange

6.5.11. TXT - Text

6.5.12. RP - Responsible Person

6.5.13. AFSDB - DCE or AFS Server

6.5.14. PX - Pointer to X.400/RFC822 mapping information


Name Server Operations Guide for BIND Release 4.9.5 : Files : Standard Resource Record Format
Previous: named.local
Next: $INCLUDE