لطفا منتظر باشید ...
A.1 Master File Format
(From RFC 1035, pages 33-35)The format of these files is a sequence of entries. Entries are
predominantly line-oriented, though parentheses can be used to
continue a list of items across a line boundary, and text literals
can contain CRLF within the text. Any combination of tabs and spaces
acts as a delimiter between the separate items that make up an entry.
The end of any line in the master file can end with a
comment. The comment starts with a semicolon (;).The following entries are defined:
blank[comment]
$ORIGIN domain-name [comment]
$INCLUDE file-name [domain-name] [comment]
domain-namerr [comment]
blankrr [comment]
Blank lines, with or without comments, are allowed anywhere in the
file.Two control entries are defined: $ORIGIN and $INCLUDE. $ORIGIN is
followed by a domain name and resets the current origin for relative
domain names to the stated name. $INCLUDE inserts the named file into
the current file and may optionally specify a domain name that sets
the relative domain name origin for the included file. $INCLUDE may
also have a comment. Note that an $INCLUDE entry never changes the
relative origin of the parent file, regardless of changes to the
relative origin made within the included file.The last two forms represent RRs. If an entry for an RR begins with a
blank, then the RR is assumed to be owned by the last stated owner.
If an RR entry begins with a domain-name,
then the owner name is reset.rr contents take one of the following forms:
[
TTL] [
class]
type RDATA
[
class] [
TTL]
type RDATA
The RR begins with optional TTL and class fields, followed by a type
and RDATA field appropriate to the type and class. Class and type use
the standard mnemonics; TTL is a decimal integer. Omitted class and
TTL values default to the last explicitly stated values. Since type
and class mnemonics are disjoint, the parse is unique.domain-names make up a large share of the
data in the master file. The labels in the domain name are expressed
as character strings and separated by dots. Quoting conventions allow
arbitrary characters to be stored in domain names. Domain names that
end in a dot are called absolute and are taken as complete. Domain
names that do not end in a dot are called relative; the actual domain
name is the concatenation of the relative part with an origin
specified in an $ORIGIN, $INCLUDE, or argument to the master
file-loading routine. A relative name is an error when no origin is
available.character-string is expressed in one of
two ways: as a contiguous set of characters without interior spaces,
or as a string beginning with " and ending with
". Inside a "-delimited string
any character can occur, except for " itself,
which must be quoted using a backslash (\).Because these files are text files, several special encodings are
necessary to allow arbitrary data to be loaded. In particular:.
Of the root.
@
A free-standing @ is used to denote the current origin.
\X
X is any character other than a digit (0-9), and \ is used to quote
that character so that its special meaning does not apply. For
example, \. can be used to place a dot character in a label (not
implemented by BIND 4.8.3).
\DDD
Each D is a digit in 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 (not implemented by BIND 4.8.3).
( )
Parentheses are used to group data that crosses a line boundary. In
effect, line terminations are not recognized within parentheses.
(BIND 4.8.3 allows parentheses only on SOA and WKS resource records.)
;
A semicolon is used to start a comment; the remainder of the line is
ignored.
A.1.1 Time to Live
(From RFC 2308, pages 7-8)The Master File format [RFC 1035 Section 5] is extended to include
the following directive:
$TTL <TTL> [comment]
All resource records appearing after the directive, and which do not
explicitly include a TTL value, have their TTL set to the TTL given in the $TTL
directive.The remaining of the current meanings, of being the TTL to be used
for negative responses, is the new defined meaning of the SOA minimum
field.
A.1.2 Character Case
(From RFC 1035, page 9)For all parts of the DNS that are part
of the official
protocol, all comparisons between character strings (e.g., labels,
domain names, etc.) are done in a case-insensitive manner. At
present, this rule is in force throughout the domain system without
exception. However, future additions beyond current usage may need to
use the full binary octet capabilities in names, so attempts to store
domain names in 7-bit ASCII or use of special bytes to terminate
labels, etc., should be avoided.
A.1.3 Types
Following is a list of common
resource record types. The textual
representation is used in master files. The binary representation is
used in DNS queries and responses. These resource records are
described on pages 13-21 of RFC 1035.
| A (address) | (From RFC 1035, page 20) |
Textual representation
owner ttl class A address
Example
localhost.movie.edu. IN A 127.0.0.1
Binary representation
Address type code: 1
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ADDRESS |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:ADDRESS
Is a 32-bit Internet address.
| CNAME (canonical name) | (From RFC 1035, page 14) |
Textual representation
owner ttl class CNAME canonical-dname
Example
wh.movie.edu. IN CNAME wormhole.movie.edu.
Binary representation
CNAME type code: 5
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ CNAME /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:CNAME
Is a domain-name that specifies the
canonical or primary name for the owner. The owner name is an alias.
| MX (mail exchanger) | (From RFC 1035, page 17) |
Textual representation
owner ttl class
MX preference exchange-dname
Example
ora.com. IN MX 0 ora.ora.com.
IN MX 10 ruby.ora.com.
IN MX 10 opal.ora.com.
Binary representation
MX type code: 15
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| PREFERENCE |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ EXCHANGE /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:PREFERENCE
Is a 16-bit integer that specifies the preference given to this RR
among others at the same owner. Lower values are preferred.
EXCHANGE
Is a domain-name that specifies a host
willing to act as a mail exchange for the owner name.
| NS (name server) | (From RFC 1035, page 18) |
Textual representation
owner ttl class NS
name-server-dname
Example
movie.edu. IN NS terminator.movie.edu
Binary representation
NS type code: 2
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ NSDNAME /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:NSDNAME
Is a domain-name that specifies a host
which should be authoritative for the specified class and domain.
| PTR (pointer) | (From RFC 1035, page 18) |
Textual representation
owner ttl class
PTR dname
Example
1.249.249.192.in-addr.arpa. IN PTR wormhole.movie.edu.
Binary representation
PTR type code: 12
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ PTRDNAME /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:PTRDNAME
Is a domain-name that points to some
location in the domain name space.
| SOA (start of authority) | (From RFC 1035, pages 19-20) |
Textual representation
owner ttl class SOA s
ource-dname mbox (serial refresh retry expire minimum)
Example
movie.edu. IN SOA terminator.movie.edu. al.robocop.movie.edu. (
1 ; Serial
10800 ; Refresh after 3 hours
3600 ; Retry after 1 hour
604800 ; Expire after 1 week
86400 ) ; Minimum TTL of 1 day
Binary representation
SOA type code: 6
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ MNAME /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ RNAME /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| SERIAL |
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| REFRESH |
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| RETRY |
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| EXPIRE |
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| MINIMUM |
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:MNAME
Is the domain-name of the name server that
was the original or primary source of data for this zone.
RNAME
Is a domain-name that specifies the
mailbox of the person responsible for this zone.
SERIAL
Is the unsigned 32-bit version number of the original copy of the
zone. Zone transfers preserve this value. This value wraps and should
be compared using sequence space arithmetic.
REFRESH
Is a 32-bit time interval before the zone should be refreshed.
RETRY
Is a 32-bit time interval that should elapse before a failed refresh
should be retried.
EXPIRE
Is a 32-bit time value that specifies the upper limit on the time
interval that can elapse before the zone is no longer authoritative.
MINIMUM
Is the unsigned 32-bit minimum TTL field that should be exported with
any RR from this zone.
| TXT (text) | (From RFC 1035, page 20) |
Textual representation
owner ttl class TXT txt-strings
Example
cujo.movie.edu. IN TXT "Location: machine room dog house"
Binary representation
TXT type code: 16
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ TXT-DATA /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:TXT-DATA
Is one or more character-strings.
A.1.4 New Types from RFC 1183
| RP (Responsible Personexperimental) |
Textual representation
owner ttl class
RP mbox-dname txt-dname
Example
; The current origin is fx.movie.edu
@ IN RP ajs.fx.movie.edu. ajs.fx.movie.edu.
bladerunner IN RP root.fx.movie.edu. hotline.fx.movie.edu.
IN RP richard.fx.movie.edu. rb.fx.movie.edu.
ajs IN TXT "Arty Segue, (415) 555-3610"
hotline IN TXT "Movie U. Network Hotline, (415) 555-4111"
rb IN TXT "Richard Boisclair, (415) 555-9612"
Binary representation
RP type code: 17
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ MAILBOX /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ TXTDNAME /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:MAILBOX
Is a domain-name that specifies the
mailbox for the responsible person.
TXTDNAME
Is a domain-name for which TXT RRs exist.
A subsequent query can be performed to retrieve the associated TXT
resource records at txt-dname.
A.1.5 New Types from RFC 1886
| AAAA (IPv6 Address) |
Textual representation
owner ttl class
AAAA ipv6-address
Example
bridgetjones.movie.edu. IN AAAA 4321:0:1:2:3:4:567:89ab
Binary representation
Address type code: 28
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| ADDRESS |
| |
| |
| |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:ADDRESS
Is a 128-bit Internet Protocol Version 6 address.
A.1.6 New Types from RFC 2052
| SRV (service location) | |
Textual representation
owner ttl class
SRV priority weight port target
Example
_http._tcp.movie.edu. IN SRV 1 2 80 www.fx.movie.edu.
IN SRV 1 1 8080 www1.fx.movie.edu.
Binary representation
SRV type code: 33
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| PRIORITY |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| WEIGHT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| PORT |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
/ TARGET /
/ /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
where:PRIORITY
Is, as for MX, the priority of this target host. A client MUST
attempt to contact the target host with the lowest-numbered priority
it can reach; target hosts with the same priority SHOULD be tried in
pseudorandom order. The range is 0-65535.
WEIGHT
Is a load-balancing mechanism. When selecting a target host among
those that have the same priority, the chance of trying this one
first SHOULD be proportional to its weight. The range of this number
is 1-65535. Domain administrators are urged to use Weight 0 when
there isn't any load balancing to do, to make the RR
easier to read for humans (less noisy).
PORT
Is the port on this target host of this service. The range is
0-65535. This is often as specified in Assigned Numbers but need not
be.
TARGET
Is, as for MX, the domain name of the target host. There MUST be one
or more A records for this name. Implementors are urged, but not
required, to return the A record(s) in the Additional Data section.
Name compression is to be used for this field. A Target of
"." means that the service is
decidedly not available at this domain.
A.1.7 Classes
(From RFC 1035, page 13)CLASS fields appear in
resource records. The following CLASS mnemonics and values are defined:IN
1: the Internet
CS
2: the CSNET class (obsoleteused only for examples in some
obsolete RFCs)
CH
3: the CHAOS class
HS
4: the Hesiod class
