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English
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dns_check_record() depends on the proper functioning of the network connection and DNS servers. If the server is unreachable or the network connection is interrupted during the DNS query, the function may fail to retrieve the DNS record, causing it to return null values.
Fix:
Check whether the server’s network connection is stable and ensure it can reach the DNS server.
Use ping or nslookup tools to test if the target DNS server is available.
If the DNS server is unreachable, contact the administrator or switch to another DNS server.
Cause:
dns_check_record() supports multiple types of DNS records, such as A, MX, TXT, etc. If you pass an incorrect or unsupported record type, the function might return null values.
Fix:
Ensure the DNS record type passed to dns_check_record() is valid. Common types include A, MX, CNAME, TXT, etc.
Use checkdnsrr() when calling the function to check if the DNS record type is correct.
Cause:
If the DNS record for the queried domain does not exist, dns_check_record() will return null. This is common when querying for domains that don’t exist or haven’t configured DNS records yet.
Fix:
Verify if the domain you’re querying is correct to avoid input errors.
Check the DNS configuration for the target domain to ensure that the appropriate records have been configured.
If it’s a domain you manage, use DNS management tools (like cPanel, Cloudflare, etc.) to view the record configuration.
Cause:
Sometimes DNS queries can be influenced by local or intermediate DNS caches. If the cached records are outdated or inaccurate, it may cause dns_check_record() to return null values.
Fix:
Clear the local DNS cache (use the ipconfig /flushdns command in the command line) to ensure that the latest DNS records are queried.
If the issue persists, try switching to a different DNS server, such as Google DNS (8.8.8.8 and 8.8.4.4) or Cloudflare DNS (1.1.1.1).
Cause:
In some cases, PHP scripts may be restricted by server permissions, preventing DNS queries. This is especially common in shared hosting or certain VPS environments, where PHP configuration might block external network requests.
Fix:
Check the disable_functions setting in the PHP configuration file (php.ini) to ensure that no network-related functions, such as dns_check_record(), are disabled.
Inspect the server’s firewall or security configurations to see if external DNS requests are being blocked.
Cause:
The dns_check_record() function accepts several parameters, including the domain and query type. If these parameters are incorrectly formatted or missing necessary values, they may lead to null values being returned.
Fix:
Ensure the first parameter passed to dns_check_record() is a valid domain.
Check that the second parameter (record type) is correctly passed and is a valid type.
<span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">dns_check_record</span></span><span>(</span><span><span class="hljs-string">'example.com'</span></span><span>, </span><span><span class="hljs-string">'A'</span></span><span>)) {
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"A record exists."</span></span><span>;
} </span><span><span class="hljs-keyword">else</span></span><span> {
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"No A record found."</span></span><span>;
}
</span></span>Cause:
Sometimes there could be logical errors in the code, causing the function to return null even when the DNS record exists. This could be due to incorrect condition checks, duplicate calls, etc.
Fix:
Carefully examine the condition checks in your code to ensure the logic is sound.
Consider printing debug information to check the function’s return values and call stack, helping you pinpoint the source of the issue.
