Validating domain in a comma separated string | Laravel | Page 1

I have string with a comma separated list of domain names, I want to ensure that the domains are valid and the domains actually exist. Here is the Custom Validation Rule I have, but the execution of checkdnrr for MX records seems to take a lot of time and causing a 504 error. Is there a simpler way to do this?

class ValidDomainListRule implements ValidationRule
{
    public function validate(string $attribute, mixed $value, Closure $fail): void
    {
        $domains = array_map('trim', explode(',', $value));

        foreach ($domains as $domain) {
            // Basic domain format validation
            if (!filter_var($domain, FILTER_VALIDATE_DOMAIN)) {
                $fail("The {$attribute} contains an invalid domain format: {$domain}.");
                return;
            }
            
            // Check if the domain exists (DNS resolution)
            if (!checkdnsrr($domain, 'ANY')) { // 'ANY' checks for any type of DNS record
                $fail("The domain '{$domain}' in {$attribute} does not appear to exist.");
                return;
            }
        }
    }
}

Any advice.

#Validating domain in a comma separated string