$string = "google.com.tr domain lookup results from whois.nic.tr server* Registrant:Google Inc.1600 Amphitheatre ParkwayMountain View CAOut of Turkey,United States of Americadns-admin@google.com+ 1-650-2530000-+ 1-650-2530001-** Administrative Contact:NIC Handle: mi154-metuOrganization Name: MarkMonitor, IncAddress: Hidden upon user requestPhone: Hidden upon user requestFax: Hidden upon user request** Technical Contact:NIC Handle: btl1-metuOrganization Name: Beril Teknoloji Bilişim Yayıncılık Ticaret A.Ş.Address: Hidden upon user requestPhone: Hidden upon user requestFax: Hidden upon user request** Billing Contact:NIC Handle: btl1-metuOrganization Name: Beril Teknoloji Bilişim Yayıncılık Ticaret A.Ş.Address: Hidden upon user requestPhone: Hidden upon user requestFax: Hidden upon user request** Domain Servers:ns1.google.comns2.google.comns3.google.com ns4.google.com** Additional Info:Created on..............: 2001-Aug-23.Expires on..............: 2019-Aug-22.";
preg_match("/\*\* Domain Servers:(.*?)\*\*/i", $string, $cikti);
preg_match_all("/[a-zA-Z0-9]+.[a-zA-Z0-9]+.[a-zA-Z]{2,3}+/i", $cikti[1], $veriler);

echo "<pre>";
print_r ($veriler[0]);
echo "</pre>";