How can PHP developers troubleshoot cookie-related issues when working with multiple domains?

When working with multiple domains, PHP developers may encounter cookie-related issues due to the default behavior of cookies being tied to a specific domain. To troubleshoot this, developers can set the cookie domain parameter to a common root domain that all domains share. This allows the cookie to be accessible across multiple domains.

// Set the cookie domain to a common root domain
$cookieDomain = '.example.com';
setcookie('cookie_name', 'cookie_value', time() + 3600, '/', $cookieDomain);