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Wednesday 13 December 2017

Master Zone DNS service configurations


To creating Master DNS for example.com zone we will add one new  zone. as below to host and configure domain, two steps to be needed

1. Edit domain entry in /etc/named.conf
2. Population zone file with RR

 

Zone definition / creation of zone in /etc/named.conf
create entry in /etc/named.conf

following configuration is for “example.com” and the Resource Record will be stored at “/var/named/example.com.zone” file

zone "example.com" IN {
    type master;
    file "example.com.zone";
};


# Edit zmailtech.com domain entry in /etc/named.conf file.
 

[root@master ~]# vim /etc/named.conf
[root@master ~]# 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.
//
// See the BIND Administrator's Reference Manual (ARM) for details about the
// configuration located in /usr/share/doc/bind-{version}/Bv9ARM.html

options {
        listen-on port 53 { 127.0.0.1; 192.168.10.2; };
        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; 192.168.10.0/24; };

        /*
         - If you are building an AUTHORITATIVE DNS server, do NOT enable recursion.
         - If you are building a RECURSIVE (caching) DNS server, you need to enable
           recursion.
         - If your recursive DNS server has a public IP address, you MUST enable access
           control to limit queries to your legitimate users. Failing to do so will
           cause your server to become part of large scale DNS amplification
           attacks. Implementing BCP38 within your network would greatly
           reduce such attack surface
        */
        recursion yes;

//      dnssec-enable yes;
//      dnssec-validation yes;

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

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

        pid-file "/run/named/named.pid";
        session-keyfile "/run/named/session.key";
};

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

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

zone "zmailtech.com" IN {
        type master;
        file "zmailtech.com.zone";
};


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

[root@master ~]#

Population / creating entry RR (Resource Record) in zone file
To populate resource record named.localhost can be used as template.

[root@master ~]# cat /var/named/named.localhost
$TTL 1D
@       IN SOA  @ rname.invalid. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        NS      @
        A       127.0.0.1
        AAAA    ::1
[root@master ~]#


For Create Zone file copy /var/named/named.localhost in /var/named/zmailtech.com.zone



[root@master ~]# cat /var/named/named.localhost > /var/named/zmailtech.com.zone

[root@master ~]# ls -l /var/named
total 20
drwxrwx---. 2 named named   23 Dec  5 12:56 data
drwxrwx---. 2 named named   60 Dec 12 21:15 dynamic
-rw-r-----. 1 root  named 2281 May 22  2017 named.ca
-rw-r-----. 1 root  named  152 Dec 15  2009 named.empty
-rw-r-----. 1 root  named  152 Jun 21  2007 named.localhost
-rw-r-----. 1 root  named  168 Dec 15  2009 named.loopback
drwxrwx---. 2 named named    6 Aug  4 13:43 slaves
-rw-r--r--. 1 root  root   152 Dec 12 21:24 zmailtech.com.zone
[root@master ~]#

Assigning proper permission and owenership on zmailtech.com.zone file.

[root@master ~]# chgrp named /var/named/zmailtech.com.zone

[root@master ~]# ls -l /var/named/
total 20
drwxrwx---. 2 named named   23 Dec  5 12:56 data
drwxrwx---. 2 named named   60 Dec 12 21:15 dynamic
-rw-r-----. 1 root  named 2281 May 22  2017 named.ca
-rw-r-----. 1 root  named  152 Dec 15  2009 named.empty
-rw-r-----. 1 root  named  152 Jun 21  2007 named.localhost
-rw-r-----. 1 root  named  168 Dec 15  2009 named.loopback
drwxrwx---. 2 named named    6 Aug  4 13:43 slaves
-rw-r--r--. 1 root  named  152 Dec 12 21:32 zmailtech.com.zone

[root@master ~]#

Edit zone file as like below  

[root@master ~]# vim /var/named/zmailtech.com.zone
[root@master ~]# cat /var/named/zmailtech.com.zone
$TTL 1D
@       IN SOA  ns1.zmailtech.com. admin.zmailtech.com. (
                                        2017121501      ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        IN      NS      ns1.zmailtech.com.
ns1     IN      A       192.168.10.2
master  IN      A       192.168.10.2
[root@master ~]#


need to restart bind (named) service after change in DNS Records 
 

[root@master ~]# systemctl restart named

Testing DNS A Record with dig command.

[root@master ~]# dig @127.0.0.1 master.zmailtech.com

; <<>> DiG 9.9.4-RedHat-9.9.4-50.el7 <<>> @127.0.0.1 master.zmailtech.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62530
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;master.zmailtech.com.          IN      A

;; ANSWER SECTION:
master.zmailtech.com.   86400   IN      A       192.168.10.2

;; AUTHORITY SECTION:
zmailtech.com.          86400   IN      NS      ns1.zmailtech.com.

;; ADDITIONAL SECTION:
ns1.zmailtech.com.      86400   IN      A       192.168.10.2

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Tue Dec 12 21:37:43 IST 2017
;; MSG SIZE  rcvd: 99

[root@master ~]#

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