fpdns(1p) on Linux
The text 6e989af50d2d, as Debian 6.0 (Squeeze) shipped it.
DNS server fingeprinting tool
Flags it lists
-
-D -
-F -
-Q -
-S -
-T -
-c -
-d -
-f -
-p -
-r -
-s -
-t -
-v