/etc/bind/db.1.168.192.in-addr.arpa. is in debian-edu-config 1.702.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 | $TTL 500
@		IN	SOA	tjener.intern. root.postoffice.intern. (
				1 ; Serialnumber
				3600	; Refresh
				1800	; Retry
				720000	; Expire
				6400 )	; Minimum TTL
			NS	tjener.intern.
			MX	10 tjener.intern.
254			PTR	ltspserver01.subnet01.intern.
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