How To Configure DNS Server In Linux CentOS by Linuxtopic

Q. How to configure dns server in linux ?
Q. step by step dns server configuration in linux ?

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IP  - 10.20.2.33
Hostname - khandwa.lokesh.com 
OS  - CentOS 6
PORT  - 53

The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. It's convert ip to name or name to ip.

Package install by Yum

yum install bind*

Open configuration file & Update

vi /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; 10.20.2.33; }; ### MASTER DNS IP ###
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; ANY; }; ### ANY ###
ALLOW-TRANSFER{ LOCALHOST; 10.20.2.34; }; #SLAVE DNS IP IF WE HAVE SLAVE DNS OTHERVISE DISABLE IT 
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";
};
INCLUDE "/ETC/NAMED.RFC1912.ZONES";
INCLUDE "/ETC/NAMED.ROOT.KEY";

Configure Zone file in

vi /etc/named.rfc1912.zone

ZONE "LOKESH.COM" IN {      #CHANGE YOUR DOMAIN NAME #
        TYPE MASTER;
        FILE "FORWARD.ZONE";    # FORWARD ZONE FILE #
        ALLOW-UPDATE { NONE; };
};
ZONE "LOCALHOST" IN {
        TYPE MASTER;
        FILE "NAMED.LOCALHOST";
        ALLOW-UPDATE { NONE; };
};
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" IN {
        TYPE MASTER;
        FILE "NAMED.LOOPBACK";
        ALLOW-UPDATE { NONE; };
};
ZONE "33.2.20.10.IN-ADDR.ARPA2.20.10.IN-ADDR.ARPA" IN {   # SET YOUR DNS IP
        TYPE MASTER;
        FILE "REVERSE.ZONEREVERSE.ZONE";     # REVERSE ZONE FILE #
        ALLOW-UPDATE { NONE; };
}
ZONE "0.IN-ADDR.ARPA" IN {
        TYPE MASTER;
        FILE "NAMED.EMPTY";
        ALLOW-UPDATE { NONE; };

Create forward & reverse Zone files

Copy named.localhost & named.loopback file

cp /var/named/named.localhost /var/named/forward.zonecp /var/named/named.loopback /var/named/reverse.zone

Configure Forward Zone

vi /var/named/forward.zone

$TTL 1D
@   IN  SOA     KHANDWA.LOKESH.COM. RNAME.INVALID. (
                             0  ;SERIAL
                             1D        ;REFRESH
                             1H        ;RETRY
                             1W      ;EXPIRE
                             3H       ;MINIMUM
)
               NS          @
               A          127.0.0.1
@       IN  NS          KHANDWA.LOKESH.COM.
@       IN  NS          SECONDARYDNS.LOKESH.COM.  # SERCONDRY DNS NAME #
@       IN  A           10.20.2.33
@       IN  A           10.20.2.34# SECONDRY DNS IP #
@       IN  A           10.20.2..102
KHANDWA       IN  A   10.20.2.33
SECONDARYDNS    IN  A   10.20.2.34
CLIENT          IN  A   10.20.2.102

Configure Reverse Zone

vi /var/named/reverse.zone

$TTL 1D
@   IN  SOA     KHANDWA.LOKESH.COM. RNAME.INVALID. (
        0  ;SERIAL
        1D        ;REFRESH
        1H        ;RETRY
        1W      ;EXPIRE
        3H )       ;MINIMUM
)
               NS          @
               A          127.0.0.1
@       IN  NS          KHANDWA.LOKESH.COM.
@       IN  NS          SECONDARYDNS.LOKESH.COM.
@       IN  PTR         LOKESH.COM.
MASTERDNS       IN  A   10.20.2.33
SECONDARYDNS    IN  A   10.20.2.34
CLIENT          IN  A   10.20.2.102
33     IN  PTR         KHANDWA.LOKESH.COM.
34     IN  PTR         SECONDARYDNS.LOKESH.COM.
102    IN  PTR        CLIENT.LOKESH.COM.

To test DNS configuration and zone files 

named-checkconf /etc/named.confnamed-checkzone lokesh.com /var/named/forward.zonenamed-checkzone lokesh.com /var/named/reverse.zone

Start the DNS service

service named startchkconfig named on

Adjust iptables to allow DNS server from outside of the network

vi /etc/sysconfig/iptables

:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -P UDP -M STATE --STATE NEW --DPORT 53 -J ACCEPT   # ADD LINE #
-A INPUT -P TCP -M STATE --STATE NEW --DPORT 53 -J ACCEPT   #ADD LINE #
-A INPUT -M STATE --STATE ESTABLISHED,RELATED -J ACCEPT

To Restart Service 

service iptables restart

To test DNS Server using dig command

dig khandwa.lokesh.com

; <<>> DIG 9.8.2RC1-REDHAT-9.8.2-0.30.RC1.EL6_6.3 <<>> KHANDWA.LOKESH.COM
;; GLOBAL OPTIONS: +CMD
;; GOT ANSWER:
;; ->>HEADER<<- OPCODE: QUERY, STATUS: NOERROR, ID: 11151
;; FLAGS: QR AA RD RA; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;KHANDWA.LOKESH.COM.            IN      A

;; ANSWER SECTION:
KHANDWA.LOKESH.COM.     86400   IN      A       10.20.2.33

;; AUTHORITY SECTION:
LOKESH.COM.             86400   IN      NS      KHANDWA.LOKESH.COM.

;; QUERY TIME: 0 MSEC
;; SERVER: 10.20.2.33#53(10.20.2.33)
;; WHEN: SAT JUL 11 21:26:14 2015
;; MSG SIZE  RCVD: 66

nslookup lokesh.com

Server: 10.20.2.33
Address: 10.20.2.33#53

Command for Check MX Record

host -t mx [hostname]

host -t MX khandwa.lokesh.com

Some Useful DNS Record

Type	Value	Description	Function
A	1	Address record	Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host.
AAAA	28	IPv6 Address record	Returns a 128-bit IPv6 address, most commonly used to map hostnames to an IP address of the host.
CNAME	5	Canonical name record	Alias of one name to another: the DNS lookup will continue by retrying the lookup with the new name.
DNSKEY	48	DNS Key Record	The key record used in DNSSEC. Uses the same format as the KEY record.
LOC	29	Location record	Specifies a geographical location associated with a domain name
MX	15	Mail exchange record	Maps a domain name to a list of message transfer agents for that domain
NS	2	Name server record	Delegates a DNS zone to use the given authoritative name servers
PTR	12	Pointer record	Pointer to a canonical name. Unlike a CNAME, DNS processing stops and just the name is returned. The most common use is for implementing reverse DNS lookups, but other uses include such things as DNS-SD.
SOA	6	Start of [a zone of] authority record	Specifies authoritative information about a DNS zone, including the primary name server, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the zone.