bind9 resolução inversa não funciona

Question

Minha resolução avançada funciona e a resolução inversa falha, incapaz de descobrir o problema. Eu aprecio se alguém apontar o erro de configuração. Aqui você vai para alguns arquivos e saída

dinesh@ubuntu:~$ nslookup 192.168.7.1
Server:     127.0.1.1
Address:    127.0.1.1#53

** server can't find 1.7.168.192.in-addr.arpa: NXDOMAIN



dinesh@ubuntu:~$ nslookup r1.lab.co.in
Server:     127.0.1.1
Address:    127.0.1.1#53

Name:   r1.lab.co.in
Address: 1.1.1.1

dinesh@ubuntu:~$ nslookup 2.2.2.2
Server:     127.0.1.1
Address:    127.0.1.1#53

** server can't find 2.2.2.2.in-addr.arpa: NXDOMAIN






dinesh@ubuntu:~$ sudo named-checkzone 168.192.in-addr.arpa /etc/bind/zones/db.192.168 
zone 168.192.in-addr.arpa/IN: loaded serial 4
OK

/etc/bind/zones/db.192.168

;
; BIND reverse data file for local loopback interface
;
$TTL    604800
@   IN  SOA ns1.lab.co.in admin.lab.co.in. (
                  3     ; Serial
             604800     ; Refresh
              86400     ; Retry
            2419200     ; Expire
             604800 )   ; Negative Cache TTL
;

; name servers
      IN      NS      ns1.lab.co.in.
      IN      NS      ns2.lab.co.in.

; PTR Records
7.1    IN      PTR     ns1.lab.co.in.    ; 192.168.7.1
7.110   IN      PTR     ns2.lab.co.in.    ; 192.168.7.110
1.1 IN      PTR     r1.lab.co.in.  ; 1.1.1.1
2.2     IN      PTR     r2.lab.co.in.  ; 2.2.2.2
3.3 IN      PTR     r3.lab.co.in.  ; 3.3.3.3
4.4 IN      PTR     r4.lab.co.in.  ; 4.4.4.4
5.5 IN      PTR     r5.lab.co.in.  ; 5.5.5.5
6.6 IN      PTR     r6.lab.co.in.  ; 6.6.6.6
7.7 IN      PTR     r7.lab.co.in.  ; 7.7.7.7
8.8 IN      PTR     r8.lab.co.in.  ; 8.8.8.8
9.9 IN      PTR     r9.lab.co.in.  ; 9.9.9.9
10.10   IN      PTR     r10.lab.co.in.  ; 10.10.10.10

named.conf.options

acl "trusted" {
        192.168.7.1;    # ns1 - can be set to localhost
        192.168.7.10;   #host1

};
options {
    directory "/var/cache/bind";

    recursion yes;                 # enables resursive queries
        allow-recursion { trusted; };  # allows recursive queries from "trusted" clients
        listen-on { 192.168.7.1;192.168.7.0/24; };   # ns1 private IP address - listen on private network only
        allow-transfer { none; };      # disable zone transfers by default

    // If there is a firewall between you and nameservers you want
    // to talk to, you may need to fix the firewall to allow multiple
    // ports to talk.  See http://www.kb.cert.org/vuls/id/800113

    // If your ISP provided one or more IP addresses for stable 
    // nameservers, you probably want to use them as forwarders.  
    // Uncomment the following block, and insert the addresses replacing 
    // the all-0's placeholder.

    //forwarders {
    //  8.8.8.8;
    //  8.8.4.4;
    //};

    //========================================================================
    // If BIND logs error messages about the root key being expired,
    // you will need to update your keys.  See https://www.isc.org/bind-keys
    //========================================================================
    dnssec-validation auto;

    auth-nxdomain no;    # conform to RFC1035
    listen-on-v6 { any; };
};

named.conf.local

//
// Do any local configuration here
//

// Consider adding the 1918 zones here, if they are not used in your
// organization
//include "/etc/bind/zones.rfc1918";


zone "lab.co.in" {
    type master;
    file "/etc/bind/zones/db.lab.co.in"; # zone file path
    allow-transfer { 192.168.7.110; };         # ns2 private IP address - secondary
};


zone "168.192.in-addr.arpa" {
    type master;
    file "/etc/bind/zones/db.192.168";  # 192.168.0.0/16 subnet
    allow-transfer { 192.168.7.110; };  # ns2 private IP address - secondary
};

/ var / log / syslog

Feb 27 15:51:28 ubuntu systemd[1]: Stopped BIND Domain Name Server.
Feb 27 15:51:29 ubuntu systemd[1]: Started BIND Domain Name Server.
Feb 27 15:51:29 ubuntu named[12665]: starting BIND 9.10.3-P4-Ubuntu <id:ebd72b3>
 -f -u bind
Feb 27 15:51:29 ubuntu named[12665]: built with '--prefix=/usr' '--mandir=/usr/s
hare/man' '--libdir=/usr/lib/i386-linux-gnu' '--infodir=/usr/share/info' '--sysc
onfdir=/etc/bind' '--localstatedir=/' '--enable-threads' '--enable-largefile' '-
-with-libtool' '--enable-shared' '--enable-static' '--with-openssl=/usr' '--with
-gssapi=/usr' '--with-gnu-ld' '--with-geoip=/usr' '--with-atf=no' '--enable-ipv6
' '--enable-rrl' '--enable-filter-aaaa' '--enable-native-pkcs11' '--with-pkcs11=
/usr/lib/i386-linux-gnu/softhsm/libsofthsm2.so' 'CFLAGS=-g -O2 -fPIE -fstack-pro
tector-strong -Wformat -Werror=format-security -fno-strict-aliasing -fno-delete-
null-pointer-checks -DNO_VERSION_DATE' 'LDFLAGS=-Wl,-Bsymbolic-functions -fPIE -
pie -Wl,-z,relro -Wl,-z,now' 'CPPFLAGS=-Wdate-time -D_FORTIFY_SOURCE=2 -DDIG_SIG
CHASE'
Feb 27 15:51:29 ubuntu named[12665]: -------------------------------------------
---------
Feb 27 15:51:29 ubuntu named[12665]: BIND 9 is maintained by Internet Systems Co
nsortium,
Feb 27 15:51:29 ubuntu named[12665]: Inc. (ISC), a non-profit 501(c)(3) public-b
enefit
Feb 27 15:51:29 ubuntu named[12665]: corporation.  Support and training for BIND
 9 are
Feb 27 15:51:29 ubuntu named[12665]: available at https://www.isc.org/support
Feb 27 15:51:29 ubuntu named[12665]: -------------------------------------------
---------
Feb 27 15:51:29 ubuntu named[12665]: adjusted limit on open files from 4096 to 1
048576
Feb 27 15:51:29 ubuntu named[12665]: found 2 CPUs, using 2 worker threads
Feb 27 15:51:29 ubuntu named[12665]: using 2 UDP listeners per interface
Feb 27 15:51:29 ubuntu named[12665]: using up to 4096 sockets
Feb 27 15:51:29 ubuntu named[12665]: loading configuration from '/etc/bind/named
.conf'
Feb 27 15:51:29 ubuntu named[12665]: reading built-in trusted keys from file '/e
tc/bind/bind.keys'
Feb 27 15:51:29 ubuntu named[12665]: initializing GeoIP Country (IPv4) (type 1) 
DB
Feb 27 15:51:29 ubuntu named[12665]: GEO-106FREE 20160408 Bu
Feb 27 15:51:29 ubuntu named[12665]: initializing GeoIP Country (IPv6) (type 12)
 DB
Feb 27 15:51:29 ubuntu named[12665]: GEO-106FREE 20160408 Bu
Feb 27 15:51:29 ubuntu named[12665]: initializing GeoIP City (IPv4) (type 2) DB
Feb 27 15:51:29 ubuntu named[12665]: GEO-106FREE 20160408 Bu
Feb 27 15:51:29 ubuntu named[12665]: GeoIP City (IPv6) (type 30) DB not availabl
e
Feb 27 15:51:29 ubuntu named[12665]: GeoIP City (IPv6) (type 31) DB not availabl
e
Feb 27 15:51:29 ubuntu named[12665]: GeoIP Region (type 3) DB not available
Feb 27 15:51:29 ubuntu named[12665]: GeoIP Region (type 7) DB not available
Feb 27 15:51:29 ubuntu named[12665]: GeoIP ISP (type 4) DB not available
Feb 27 15:51:29 ubuntu named[12665]: GeoIP Org (type 5) DB not available
Feb 27 15:51:29 ubuntu named[12665]: initializing GeoIP AS (type 9) DB
Feb 27 15:51:29 ubuntu named[12665]: GEO-106FREE 20160408 Bu
Feb 27 15:51:29 ubuntu named[12665]: GeoIP Domain (type 11) DB not available
Feb 27 15:51:29 ubuntu named[12665]: GeoIP NetSpeed (type 10) DB not available
Feb 27 15:51:29 ubuntu named[12665]: using default UDP/IPv4 port range: [32768, 
60999]
Feb 27 15:51:29 ubuntu named[12665]: using default UDP/IPv6 port range: [32768, 
60999]
Feb 27 15:51:29 ubuntu named[12665]: listening on IPv6 interfaces, port 53
Feb 27 15:51:29 ubuntu named[12665]: listening on IPv4 interface tap0, 192.168.7
.1#53
Feb 27 15:51:29 ubuntu named[12665]: generating session key for dynamic DNS
Feb 27 15:51:29 ubuntu named[12665]: sizing zone task pool based on 7 zones
Feb 27 15:51:29 ubuntu named[12665]: using built-in root key for view _default
Feb 27 15:51:29 ubuntu named[12665]: set up managed keys zone for view _default,
 file 'managed-keys.bind'
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 10.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 16.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 17.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 18.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 19.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 20.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 21.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 22.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 23.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 24.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 25.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 26.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 27.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 28.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 29.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 30.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 31.172.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 64.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 65.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 66.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 67.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 68.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 69.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 70.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 71.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 72.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 73.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 74.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 75.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 76.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 77.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 78.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 79.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 80.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 81.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 82.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 83.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 84.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 85.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 86.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 87.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 88.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 89.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 90.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 91.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 92.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 93.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 94.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 95.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 96.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 97.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 98.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 99.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 100.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 101.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 102.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 103.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 104.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 105.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 106.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 107.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 108.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 109.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 110.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 111.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 112.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 113.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 114.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 115.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 116.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 117.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 118.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 119.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 120.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 121.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 122.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 123.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 124.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 125.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 126.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 127.100.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 254.169.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 2.0.192.IN-ADDR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 100.51.198.IN-ADDR.AR
PA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 113.0.203.IN-ADDR.ARP
A
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 255.255.255.255.IN-AD
DR.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 0.0.0.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 1.0.0.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: D.F.IP6.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 8.E.F.IP6.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 9.E.F.IP6.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: A.E.F.IP6.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: B.E.F.IP6.ARPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: 8.B.D.0.1.0.0.2.IP6.A
RPA
Feb 27 15:51:29 ubuntu named[12665]: automatic empty zone: EMPTY.AS112.ARPA
Feb 27 15:51:29 ubuntu named[12665]: configuring command channel from '/etc/bind
/rndc.key'
Feb 27 15:51:29 ubuntu named[12665]: command channel listening on 127.0.0.1#953
Feb 27 15:51:29 ubuntu named[12665]: configuring command channel from '/etc/bind
/rndc.key'
Feb 27 15:51:29 ubuntu named[12665]: command channel listening on ::1#953
Feb 27 15:51:29 ubuntu named[12665]: managed-keys-zone: journal file is out of d
ate: removing journal file
Feb 27 15:51:29 ubuntu named[12665]: managed-keys-zone: loaded serial 92
Feb 27 15:51:29 ubuntu named[12665]: zone 0.in-addr.arpa/IN: loaded serial 1
Feb 27 15:51:29 ubuntu named[12665]: zone 127.in-addr.arpa/IN: loaded serial 1
Feb 27 15:51:29 ubuntu named[12665]: zone 168.192.in-addr.arpa/IN: loaded serial
 4
Feb 27 15:51:29 ubuntu named[12665]: zone lab.co.in/IN: loaded serial 3
Feb 27 15:51:29 ubuntu named[12665]: zone 255.in-addr.arpa/IN: loaded serial 1
Feb 27 15:51:29 ubuntu named[12665]: zone localhost/IN: loaded serial 2
Feb 27 15:51:29 ubuntu named[12665]: all zones loaded
Feb 27 15:51:29 ubuntu named[12665]: running
Feb 27 15:51:29 ubuntu named[12665]: zone lab.co.in/IN: sending notifies (serial
 3)

    

Answer 1

Conforme determinamos nos comentários, seu problema era que sua zona reversa não continha os dados que você achava que continham. Você também teve algum tipo de problema de número de série, em que você nos mostrou zonas com número de série 3, mas verificações de zona e logs de carga de zona para o número de série 4.

Quando você tentou procurar o registro reverso para 192.168.7.1:

dinesh@ubuntu:~$ nslookup 192.168.7.1
Server:     127.0.1.1
Address:    127.0.1.1#53

** server can't find 1.7.168.192.in-addr.arpa: NXDOMAIN

o servidor DNS disse "nenhum registro existe". Observe que o endereço que está tentando procurar (um RR PTR para) é 1.7.168.192.in-addr.arpa . Então, vamos comparar isso com o que você configurou seu servidor DNS.

Você tem uma zona 168.192.in-addr.arpa , então existe um lugar para qualquer coisa abaixo disso. Vamos ver o que você está servindo nessa zona.

7.1    IN      PTR     ns1.lab.co.in.    ; 192.168.7.1

A origem padrão de um arquivo de zona é o nome da zona, e a origem é anexada a qualquer nome não qualificado (em que "totalmente qualificado" significa "terminado por um período final") nessa zona. (Isso é muito útil particularmente para as zonas de redirecionamento, pois permite usar o mesmo arquivo de zona para muitas zonas similares.) Portanto, o acima é o mesmo que:

7.1.168.192.in-addr.arpa.  IN PTR  ns1.lab.co.in.    ; 192.168.7.1

7.1.168.192.in-addr.arpa é o local de registro reverso para 192.168.1.7, não 192.168.7.1. Em zonas DNS reversas, a ordem de todos os octetos do endereço IP é invertida. Isso pode ser uma fonte significativa de confusão quando você tem zonas DNS reversas de vários octetos. O comentário está mentindo para você.

Como sugeri nos comentários, a maneira de determinar que este é o problema é simplesmente procurar o endereço em que você está servindo um registro reverso, ou seja, 192.168.1.7, e veja se isso mostra o nome que você espera para 192.168.7.1. Como aparentemente aconteceu, a solução é consertar sua zona reversa invertendo a ordem do octeto. Em outras palavras, você precisa alterar o arquivo da zona inversa para dizer:

1.7    IN      PTR     ns1.lab.co.in.    ; 192.168.7.1

Uma vez que você faça isso, e aumente o número de série da zona (SOA) para um valor maior que aquele em qualquer um dos escravos (no seu caso, isso é apenas um), ou force uma atualização da zona em todos os escravos. , as pesquisas inversas para 192.168.7.1 devem render o resultado esperado ns1.lab.co.in. .