Description
array
dns_get_record ( string hostname [, int type [, array &authns, array &addtl]])
Note:
This function is not implemented on Windows platforms. Try the
PEAR class
Net_DNS.
This function returns an array of associative arrays. Each associative array contains
at minimum the following keys:
Table 1. Basic DNS attributes
| Attribute | Meaning |
|---|
| host |
The record in the DNS namespace to which the rest of the associated data refers.
|
| class |
dns_get_record() only returns Internet class records and as
such this parameter will always return IN.
|
| type |
String containing the record type. Additional attributes will also be contained
in the resulting array dependant on the value of type. See table below.
|
| ttl |
Time To Live remaining for this record. This will not equal
the record's original ttl, but will rather equal the original ttl minus whatever
length of time has passed since the authoritative name server was queried.
|
hostname should be a valid DNS hostname such
as "www.example.com". Reverse lookups can be generated using in-addr.arpa
notation, but gethostbyaddr() is more suitable for
the majority of reverse lookups.
By default, dns_get_record() will search for any resource
records associated with hostname. To limit the
query, specify the optional type parameter.
type may be any one of the following:
DNS_A, DNS_CNAME,
DNS_HINFO, DNS_MX,
DNS_NS, DNS_PTR,
DNS_SOA, DNS_TXT,
DNS_AAAA, DNS_SRV,
DNS_NAPTR, DNS_A6,
DNS_ALL or DNS_ANY.
The default is DNS_ANY.
Note:
Because of eccentricities in the performance of libresolv
between platforms, DNS_ANY will not
always return every record, the slower DNS_ALL
will collect all records more reliably.
The optional third and fourth arguments to this function,
authns and addtl
are passed by reference and, if given, will be populated with
Resource Records for the Authoritative Name Servers,
and any Additional Records respectively.
See the example below.
Table 2. Other keys in associative arrays dependant on 'type'
| Type | Extra Columns |
|---|
| A |
ip: An IPv4 addresses in dotted decimal notation.
|
| MX |
pri: Priority of mail exchanger.
Lower numbers indicate greater priority.
target: FQDN of the mail exchanger.
See also dns_get_mx().
|
| CNAME |
target: FQDN of location in DNS namespace to which
the record is aliased.
|
| NS |
target: FQDN of the name server which is authoritative
for this hostname.
|
| PTR |
target: Location within the DNS namespace to which
this record points.
|
| TXT |
txt: Arbitrary string data associated with this record.
|
| HINFO |
cpu: IANA number designating the CPU of the machine
referenced by this record.
os: IANA number designating the Operating System on
the machine referenced by this record.
See IANA's Operating System
Names for the meaning of these values.
|
| SOA |
mname: FQDN of the machine from which the resource
records originated.
rname: Email address of the administrative contain
for this domain.
serial: Serial # of this revision of the requested
domain.
refresh: Refresh interval (seconds) secondary name
servers should use when updating remote copies of this domain.
retry: Length of time (seconds) to wait after a
failed refresh before making a second attempt.
expire: Maximum length of time (seconds) a secondary
DNS server should retain remote copies of the zone data without a
successful refresh before discarding.
minimum-ttl: Minimum length of time (seconds) a
client can continue to use a DNS resolution before it should request
a new resolution from the server. Can be overridden by individual
resource records.
|
| AAAA |
ipv6: IPv6 address
|
| A6(PHP >= 5.1.0) |
masklen: Length (in bits) to inherit from the target
specified by chain.
ipv6: Address for this specific record to merge with
chain.
chain: Parent record to merge with
ipv6 data.
|
| SRV |
pri: (Priority) lowest priorities should be used first.
weight: Ranking to weight which of commonly prioritized
targets should be chosen at random.
target and port: hostname and port
where the requested service can be found.
For additional information see: RFC 2782
|
| NAPTR |
order and pref: Equivalent to
pri and weight above.
flags, services, regex,
and replacement: Parameters as defined by
RFC 2915.
|
Note:
Per DNS standards, email addresses are given in user.host format (for
example: hostmaster.example.com as opposed to hostmaster@example.com),
be sure to check this value and modify if necessary before using it
with a functions such as mail().
Example 1. Using dns_get_record()
<?php
$result = dns_get_record("php.net");
print_r($result);
?>
|
Produces output similar to the following:
Array
(
[0] => Array
(
[host] => php.net
[type] => MX
[pri] => 5
[target] => pair2.php.net
[class] => IN
[ttl] => 6765
)
[1] => Array
(
[host] => php.net
[type] => A
[ip] => 64.246.30.37
[class] => IN
[ttl] => 8125
)
) |
|
Since it's very common to want the IP address of a mail server
once the MX record has been resolved, dns_get_record()
also returns an array in addtl which
contains associate records. authns
is returned as well containing a list of authoritative name
servers.
Example 2. Using dns_get_record() and DNS_ANY
<?php
/* Request "ANY" record for php.net,
and create $authns and $addtl arrays
containing list of name servers and
any additional records which go with
them */
$result = dns_get_record("php.net", DNS_ANY, $authns, $addtl);
echo "Result = ";
print_r($result);
echo "Auth NS = ";
print_r($authns);
echo "Additional = ";
print_r($addtl);
?>
|
Produces output similar to the following:
Result = Array
(
[0] => Array
(
[host] => php.net
[type] => MX
[pri] => 5
[target] => pair2.php.net
[class] => IN
[ttl] => 6765
)
[1] => Array
(
[host] => php.net
[type] => A
[ip] => 64.246.30.37
[class] => IN
[ttl] => 8125
)
)
Auth NS = Array
(
[0] => Array
(
[host] => php.net
[type] => NS
[target] => remote1.easydns.com
[class] => IN
[ttl] => 10722
)
[1] => Array
(
[host] => php.net
[type] => NS
[target] => remote2.easydns.com
[class] => IN
[ttl] => 10722
)
[2] => Array
(
[host] => php.net
[type] => NS
[target] => ns1.easydns.com
[class] => IN
[ttl] => 10722
)
[3] => Array
(
[host] => php.net
[type] => NS
[target] => ns2.easydns.com
[class] => IN
[ttl] => 10722
)
)
Additional = Array
(
[0] => Array
(
[host] => pair2.php.net
[type] => A
[ip] => 216.92.131.5
[class] => IN
[ttl] => 6766
)
[1] => Array
(
[host] => remote1.easydns.com
[type] => A
[ip] => 64.39.29.212
[class] => IN
[ttl] => 100384
)
[2] => Array
(
[host] => remote2.easydns.com
[type] => A
[ip] => 212.100.224.80
[class] => IN
[ttl] => 81241
)
[3] => Array
(
[host] => ns1.easydns.com
[type] => A
[ip] => 216.220.40.243
[class] => IN
[ttl] => 81241
)
[4] => Array
(
[host] => ns2.easydns.com
[type] => A
[ip] => 216.220.40.244
[class] => IN
[ttl] => 81241
)
) |
|
See also
dns_get_mx(), and
dns_check_record()
