problema de resolução reversa do bind9

eu uso o bind para configuração simples na minha lan, apenas um cache para o domínio externo e o resolvedor interno da LAN , o problema é que a saída do resolvedor reverso está errada, ele deve retornar apenas o nome do domínio; parece que por algum erro o servidor não encontra recursos para responder corretamente, mas nos logs não encontrei nenhum erro; Colei aqui abaixo a configuração e saída do nslookup:
output nslookup:

$ nslookup server1.example.com

Server:     192.168.1.131
Address:    192.168.1.131#53

Name:   server1.example.com
Address: 192.168.1.130

$ nslookup 192.168.1.130 

130.1.168.192.in-addr.arpa  name = server1.example.com.1.168.192.in-addr.arpa.

configuração de ligação:

// This is the primary configuration file for the BIND DNS server named.

options {
    directory "/opt/etc/bind";
    pid-file "/opt/etc/bind/named.pid";

    query-source address * port 53;

    forwarders {
        // OPENDNS dns
        208.67.222.222;
        208.67.220.220;
        // GOOGLE dns
        8.8.8.8;
        8.8.4.4;
    };

    auth-nxdomain no;    # conform to RFC1035
};

logging {
        channel update_debug {
                file "/var/log/bind_update_debug.log" versions 3 size 100k;
                severity debug;
                print-severity  yes;
                print-time      yes;
        };
        channel security_info {
                file "/var/log/bind_security_info.log" versions 1 size 100k;
                severity info;
                print-severity  yes;
                print-time      yes;
        };
        channel bind_log {
                file "/var/log/bind.log" versions 3 size 1m;
                severity info;
                print-category  yes;
                print-severity  yes;
                print-time      yes;
        };
        channel query_log {
            file "/var/log/bind_query.log" versions 3 size 1m;
            severity debug 3;
            print-category  yes;
                    print-severity  yes;
            print-time yes;
        };

        category default { bind_log; };
        category queries { query_log; };
        category lame-servers { null; };
        category update { update_debug; };
        category update-security { update_debug; };
        category security { security_info; };
};

// prime the server with knowledge of the root servers
zone "." {
    type hint;
    file "/etc/bind/db.root";
};

// be authoritative for the localhost forward and reverse zones, and for
// broadcast zones as per RFC 1912

zone "localhost" {
    type master;
    file "/etc/bind/db.local";
};

zone "127.in-addr.arpa" {
    type master;
    file "/etc/bind/db.127";
};

zone "0.in-addr.arpa" {
    type master;
    file "/etc/bind/db.0";
};

zone "255.in-addr.arpa" {
    type master;
    file "/etc/bind/db.255";
};

zone "example.com" {
    type master;
    file "/etc/bind/db.example.com";
    notify no;
};

zone "1.168.192.in-addr.arpa" {
    type master;
    file "/etc/bind/db.192";
    notify no;
};

db.example.com:

;
; BIND data file for local loopback interface
;
$TTL    604800
@   IN  SOA example.com. admin.example.com. (
                  2     ; Serial
                 1D     ; Refresh
                 1H     ; Retry
                 1W     ; Expire
                 3H )   ; Negative Cache TTL

; name server - NS records
    IN  NS  ns.example.com.

; name server - A records
ns  IN  A   192.168.1.131

; 192.168.1.0/255 - A records
laptop  IN  A   192.168.1.102
server1 IN  A   192.168.1.130
server2 IN  A   192.168.1.131
router  IN  A   192.168.1.1

db.192:

;
; BIND reverse data file for empty rfc1918 zone 
;
$TTL    604800
@   IN  SOA example.com. admin.example.com. (
                  2     ; Serial
                 1D     ; Refresh
                 1H     ; Retry
                 1W     ; Expire
                 3H )   ; Negative Cache TTL
; name server
    IN  NS  ns.example.com.

; name server PTR record
131 IN  PTR ns.example.com

; PTR Records
102 IN  PTR laptop.example.com
130 IN  PTR server1.example.com
131 IN  PTR server2.example.com
1   IN  PTR router.example.com

Alguém pode sugerir onde está o erro? É um erro de configuração trivial? THX