PHP dns_get_record Function

last modified April 4, 2025

The PHP dns_get_record function retrieves DNS records for a given host. It provides detailed DNS information for analysis and validation.

Basic Definition

dns_get_record fetches DNS resource records associated with a host. It can retrieve various record types like A, MX, CNAME, TXT, etc.

Syntax: dns_get_record(string $hostname, int $type = DNS_ANY, array &$authns = null, array &$addtl = null, bool $raw = false): array|false. Returns an array of records or false on failure.

Retrieving All DNS Records

This example shows how to get all DNS records for a domain.

all_records.php

<?php

declare(strict_types=1);

$domain = “example.com”; $records = dns_get_record($domain);

echo “DNS records for $domain:\n”; print_r($records);

This fetches all available DNS records for the domain. The result is an array containing all record types. Each record has type-specific fields.

Getting Specific Record Types

This demonstrates retrieving only MX (Mail Exchange) records for a domain.

mx_records.php

<?php

declare(strict_types=1);

$domain = “example.com”; $mx_records = dns_get_record($domain, DNS_MX);

echo “MX records for $domain:\n”; foreach ($mx_records as $record) { echo “Priority: {$record[‘pri’]}, Target: {$record[’target’]}\n”; }

MX records specify mail servers for a domain. This example extracts priority and target server from each MX record. Useful for email configuration checks.

Checking TXT Records

This example retrieves TXT records, often used for verification and SPF.

txt_records.php

<?php

declare(strict_types=1);

$domain = “example.com”; $txt_records = dns_get_record($domain, DNS_TXT);

echo “TXT records for $domain:\n”; foreach ($txt_records as $record) { echo “TXT: {$record[’txt’]}\n”; }

TXT records contain arbitrary text data. Commonly used for domain verification, SPF records, and DKIM configuration. This extracts all TXT entries.

Getting A and AAAA Records

This shows how to retrieve both IPv4 (A) and IPv6 (AAAA) address records.

ip_records.php

<?php

declare(strict_types=1);

$host = “www.example.com”; $ip_records = dns_get_record($host, DNS_A + DNS_AAAA);

echo “IP records for $host:\n”; foreach ($ip_records as $record) { $ip = $record[’type’] == ‘A’ ? $record[‘ip’] : $record[‘ipv6’]; echo “{$record[’type’]}: $ip\n”; }

A records contain IPv4 addresses, AAAA contain IPv6. This combines both types to get all IP addresses associated with a hostname. Useful for connectivity tests.

Advanced DNS Analysis

This example performs comprehensive DNS analysis with authoritative nameservers.

advanced_dns.php

<?php

declare(strict_types=1);

$domain = “example.com”; $authns = []; $addtl = [];

$records = dns_get_record($domain, DNS_ALL, $authns, $addtl);

echo “Primary records:\n”; print_r($records);

echo “\nAuthoritative nameservers:\n”; print_r($authns);

echo “\nAdditional records:\n”; print_r($addtl);

This retrieves all records plus authoritative nameserver information. The $authns parameter returns NS records. $addtl contains additional relevant records. Useful for in-depth DNS troubleshooting.

Best Practices

• Error Handling: Always check for false return value

• Caching: Cache results to avoid repeated DNS queries

• Timeouts: Be aware of potential DNS query timeouts

• Record Validation: Verify required fields exist in results

• Security: Sanitize input to prevent DNS poisoning

Source

PHP dns_get_record Documentation

This tutorial covered the PHP dns_get_record function with practical examples for DNS record retrieval and analysis in various scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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