是的，您可以像访问者的页面解析一样。

您需要自己的DNS服务器并强制用户解决唯一的dns名称。如果用户尝试解决它，那么它们将泄漏给您的DNS服务器自己的DNS服务器地址。 DNS服务器旁边必须共享关于您的网络应用程序的唯一dns名称的信息。

Detecting visitor IP is easy. But how about detecting DNS server ips of a visitor ?

I found this PHP function, however it finds only domain names' DNS.

dns_get_record("website.com", DNS_ANY);

Is it possible to detect visitor DNS server ?

Yes, you can, like detecting page resolution of visitors.

You need own DNS server and force user to resolve unique dns name. If user tried to resolve it then they will leaks to your DNS server own DNS server address. Next to DNS server have to share information who asked about the unique dns name to your web apps.