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<?php function getIPStringForFullDNS($ip, $class) { $limits = array('A' => -3, 'B' => -2, 'C' => -1, 'D' => 0); $limit = $limits[$class]; $ip = implode('.', explode('.', $ip, $limit)); $ip .= str_repeat('.*', abs($limit)); return $ip; } echo getIPStringForFullDNS('158.58.169.254', 'A') . '<br>'; echo getIPStringForFullDNS('158.58.169.254', 'B') . '<br>'; echo getIPStringForFullDNS('158.58.169.254', 'C') . '<br>'; echo getIPStringForFullDNS('158.58.169.254', 'D') . '<br>';

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