In PHP, dns_get_mx() helps with runtime and application data. Retrieves mail exchanger hostnames and priorities using a DNS lookup, with results depending on live DNS.
What Is dns_get_mx() in PHP?
The function or method has a specific purpose: Retrieves mail exchanger hostnames and priorities using a DNS lookup, with results depending on live DNS. The following examples show the main call, one additional situation, and an application-style use.
Syntax:
<?php
dns_get_mx(string $hostname, $hosts, $weights = ...) : bool
Parameters and Return Value
$hostname(string) — argument used by this API to perform its operation; required.$hosts(mixed) — argument used by this API to perform its operation; required.$weights(mixed) — argument used by this API to perform its operation; optional.
Example 1: Basic Usage
Retrieves mail exchanger hostnames and priorities using a DNS lookup, with results depending on live DNS.
<?php
$mailServers = [];
$priorities = [];
$result = dns_get_mx("example.com", $mailServers, $priorities);
var_dump($result);
This example demonstrates the central operation. The final output depends on the supplied input and, where relevant, the runtime or connected service.
Example 2: Handling a Different Case
<?php
$mailServers = [];
$priorities = [];
$result = dns_get_mx("example.net", $mailServers, $priorities);
var_dump($result);
The second example focuses on a different input or failure condition, so the behavior can be distinguished from the basic case.
Practical Example
<?php
$mailServers = [];
$priorities = [];
$result = dns_get_mx("example.org", $mailServers, $priorities);
var_dump($result);
The practical example demonstrates how the same subject fits into a larger application. Use your own file paths, endpoints and validated inputs rather than copying sample settings directly.
Important Behavior and Edge Cases
- Retrieves mail exchanger hostnames and priorities using a DNS lookup, with results depending on live DNS.
- Check the return value and exceptions for failure before using the result. If an extension or external system is required, the example only works when that dependency is available. Network outcomes are not deterministic and responses should not be assumed to be successful.
- Use the documented return type and handle false, null and exceptions according to the specific call.
Comparison With Related Functions
| Approach | Difference |
|---|---|
| dns_get_mx | Retrieves mail exchanger hostnames and priorities using a DNS lookup, with results depending on live DNS. |
| function_exists | Checks that a PHP function name is available; does not perform this operation. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Ignoring errors from dns_get_mx | Check the actual result and handle the expected error path. |
| Using the demonstration unchanged in production | Adapt file paths, configuration, authentication and permission rules to the application. |
| Treating input or returned data as trusted | Apply validation at input boundaries and context-aware escaping at output boundaries. |
Key Takeaways
- Retrieves mail exchanger hostnames and priorities using a DNS lookup, with results depending on live DNS.
- Check the return value and exceptions for failure before using the result. If an extension or external system is required, the example only works when that dependency is available. Network outcomes are not deterministic and responses should not be assumed to be successful.
- Use the documented return type and handle false, null and exceptions according to the specific call.
Retrieves mail exchanger hostnames and priorities using a DNS lookup, with results depending on live DNS. Use this approach when its capabilities and constraints match the application. Handle invalid data, failure conditions and resource cleanup explicitly.