DNS reverse lookup issue

Linux and Unix-Like Red Hat
1

Hi guys. Ok so let me lay out my configs. I can do a NSlookup from client to server BUT NOT a reverse lookup.

DNS server: Optimus.jaydomain.com
IP : 192.168.1.50

DNS Client: Megatron.jaydomain.com
IP : 192.168.1.60

On Sever:

[root@Optimus etc]# cat /etc/named.conf
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//

options {
        listen-on port 53 { 127.0.0.1; 192.168.1.50; };
        listen-on-v6 port 53 { ::1; };
        directory       "/var/named";
        dump-file       "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
        allow-query     { localhost; 192.168.1.0/24; };
        recursion yes;

        dnssec-enable yes;
        dnssec-validation yes;
        dnssec-lookaside auto;

        /* Path to ISC DLV key */
        bindkeys-file "/etc/named.iscdlv.key";

        managed-keys-directory "/var/named/dynamic";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
        type hint;
        file "named.ca";
};

zone "jaydomain.com" IN {
        type master;
        file "/var/named/fwd.jaydomain.com";
        allow-update { none; };
};

zone "1.168.192.in-addr.arpa" IN {
        type master;
        file "/var/named/rev.jaydomain.com";
        allow-update { none; };
};




include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

[root@Optimus etc]# cat /var/named/fwd.jaydomain.com
$TTL 86400
@   IN  SOA     Optimus.jaydomain.com. root.jaydomain.com. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@ IN  NS      Optimus.jaydomain.com.

Optimus IN A 192.168.1.50

[root@Optimus etc]# cat /var/named/rev.jaydomain.com
$TTL 86400
@   IN  SOA     Optimus.jaydomain.com. root.jaydomain.com. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@ IN  NS      Optimus.jaydomain.com.

Optimus IN A 192.168.1.50

100       IN  PTR     Optimus.jaydomain.com.

[root@Optimus etc]# service named status
version: 9.8.2rc1-RedHat-9.8.2-0.23.rc1.el6_5.1
CPUs found: 1
worker threads: 1
number of zones: 21
debug level: 0
xfers running: 0
xfers deferred: 0
soa queries in progress: 0
query logging is OFF
recursive clients: 0/0/1000
tcp clients: 0/100
server is up and running
named-sdb (pid  22191) is running...

On client:

[root@Megatron ~]# cat /etc/resolv.conf
search jaydomain.com

nameserver 192.168.1.50

From client:

[root@Megatron ~]# nslookup Optimus.jaydomain.com
Server:         192.168.1.50
Address:        192.168.1.50#53

Name:   Optimus.jaydomain.com
Address: 192.168.1.50

[root@Megatron ~]# nslookup 192.168.1.50
Server:         192.168.1.50
Address:        192.168.1.50#53

** server can't find 50.1.168.192.in-addr.arpa.: NXDOMAIN

What seems to be the problem ?

2

Highlighted should be 50

1 Like
3

It worked. Thank you. Can you brief me on why you did that. It will be highly appreciated :slight_smile:

Im new to DNS.

4

The reverse zone is the opposite to a forward zone, reversing as well the ip

50.1.168.192 IN  PTR Optimus.jaydomain.com.

For abbreviation sake, most of the time you'll see just the last octet of the unreversed ip.

50 IN PTR Optimus.jaydomain.com.

Based on that information, you figure out if

Optimus IN A 192.168.1.50

which you have in /var/named/rev.jaydomain.com belong there or not

5

I see. Makes perfect sense. Thank you so much for your help Aia :slight_smile: