Broken reverse DNS - after recent bind upgrade?

[Terry Boon <terry@counterfactual.org>]

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I run a network of two machines on Debian 2.2 (potato).  apt-get
upgraded bind this evening, and since then, reverse name lookup on the
master name server for my domain has been broken.

The machines are as follows:

   poulenc (172.16.0.1)
   prokofiev (172.16.0.2)

poulenc is the master name server for the domain
herts.counterfactual.org (not visible to the outside world).

The logs (extract below) show that bind now has some problem upon
reading in the configuration files.  Error messages include "...not at
zone top..." and "...outside zone...".

Does anyone have ideas as to why this has suddenly stopped working and
generated these error messages?

Many thanks for any help.

=== Extract from /var/log/syslog (formatted for clarity) ===

Jan 29 22:04:54 poulenc named[517]: Zone "0.16.172.in-addr.arpa" (file
  /etc/bind/db.172.16.0): No default TTL ($TTL <value>) set, using SOA
  minimum instead

Jan 29 22:04:54 poulenc named[517]: /etc/bind/db.172.16.0:5: SOA for
  "172.16.0.in-addr.arpa" not at zone top "0.16.172.in-addr.arpa"

Jan 29 22:04:54 poulenc named[517]: /etc/bind/db.172.16.0:10: data
  "172.16.0.in-addr.arpa" outside zone "0.16.172.in-addr.arpa"
  (ignored)

Jan 29 22:04:54 poulenc named[517]: master zone
   "0.16.172.in-addr.arpa" (IN) rejected due to errors (serial 5)


=== Extract from /etc/bind/named.conf ===

zone "0.16.172.in-addr.arpa" in {
	type master;
	file "/etc/bind/db.172.16.0";
};


=== Extract from db.172.16.0 ===

; BIND master database file
; 172.16.0
; Created by Terry Boon on 7 January 2001

172.16.0.in-addr.arpa. IN SOA poulenc.herts.counterfactual.org. terry.counterfactual.org (
	5	; Serial
	10800	; Refresh after 3 hours
	3600	; Retry after 1 hour
	604800	; Expire after 1 week
	86400 )	; Minimum TTL of 1 day

;
; Name servers
;

0.16.172.in-addr.arpa.	IN NS	prokofiev.herts.counterfactual.org.
0.16.172.in-addr.arpa.	IN NS	poulenc.herts.counterfactual.org.

;
; Addresses point to canonical names
; 

1.0.16.172.in-addr.arpa.	IN PTR	poulenc.herts.counterfactual.org.
2.0.16.172.in-addr.arpa.	IN PTR	prokofiev.herts.counterfactual.org.

=== End extracts ===

- -- 
Terry Boon, Hertfordshire, UK
terry@counterfactual.org 
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