These characters have special meanings in resource records:
.
A free-standing dot in the ``name'' field refers to the current zone.
@
A free-standing ``@'' in the ``name''
field denotes the current origin.
You can use origins within configuration files as a shorthand for
fully qualified domain names.
..
Two free-standing dots represent the null
domain name of the root when used in the ``name'' field.
\X
Here X is any character other than a digit (0-9), and
\X escapes that character so that its
special meaning does not apply.
For example, \. can be used to place a dot character in a label.
\DDD
Here each D is a digit, and \DDD
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.
;
A semicolon starts a comment; the remainder of the line is ignored.
*
An asterisk signifies a wildcard. Wildcarding is only meaningful for
some resource record types, notably MX, and then only in
the ``name'' field. Do not use an asterisk in the data field.
Anywhere a name appears, either in the ``name'' field or in a data field
defined to contained names, the current origin is appended if the name
does not end with a ''.''. This is useful for appending
the current zone name to the data, such as machine names, but can
cause problems when you do not want this to happen. The following rule
helps avoid this problem: if the name is not in the zone for which
you are creating the data file, end the name with a ``.''.