feat: implement DNS server fingerprinting (HAN-384) (#10)

internal/output/text.go

@@ -99,7 +99,13 @@ func (f *textFormatter) writeServers(results []traverse.TraversalResult) error {
 
 	for _, name := range names {
 		for _, ip := range servers[name] {
-			if _, err := fmt.Fprintf(f.w, "%*s: %-15s\n", width, name, ip); err != nil {
+			line := fmt.Sprintf("%*s: %-15s", width, name, ip)
+			if f.cfg.ShowVersions {
+				if version, ok := f.cfg.Fingerprints[ip]; ok && version != "" {
+					line += "  " + version
+				}
+			}
+			if _, err := fmt.Fprintln(f.w, line); err != nil {
 				return err
 			}
 		}