🌐How to Configure DNS Server

Introduction

DNS

The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.

Each device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4)

How does DNS Work

The process of DNS resolution involves converting a hostname (such as www.example.com) into a computer-friendly IP address (such as 192.168.1.1). An IP address is given to each device on the Internet, and that address is necessary to find the appropriate Internet device - like a street address is used to find a particular home. When a user wants to load a webpage, a translation must occur between what a user types into their web browser (example.com) and the machine-friendly address necessary to locate the example.com webpage.

In order to understand the process behind the DNS resolution, it’s important to learn about the different hardware components a DNS query must pass between. For the web browser, the DNS lookup occurs "behind the scenes" and requires no interaction from the user’s computer apart from the initial request.

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Configuration

DNS Server

Install Package

sudo yum install bind bind-utils -y

Configure DNS

sudo vi /etc/named.conf

## Add on line 12
options {
        listen-on port 53 { 127.0.0.1; 192.168.8.100; };           ## your ip address
        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";
        recursing-file  "/var/named/data/named.recursing";
        secroots-file   "/var/named/data/named.secroots";
        allow-query     { localhost; 192.168.8.100;};              ## your ip address

## Add on line 43
        pid-file "/run/named/named.pid";
        session-keyfile "/run/named/session.key";
        forwarders {
        192.168.8.1;                                               ## your gateway
        8.8.8.8;
        8.8.4.4;
        };
        
## Add on line 64
zone "centosrizwan.com" IN {
        type master;
        file "/var/named/db.centosrizwan.com";                    ## your db.file
        allow-update { none; };
};

zone "100.8.168.in-addr.arpa" IN {
        type master;
        file "/var/named/db.100.8.168";                           ## your db.file
        allow-update { none; };
};

Create DB File for DNS Forward

db.domain

sudo vi /var/named/db.(your-domain)

;
; BIND data file for local loopback interface
;
$TTL    604800
@       IN      SOA     centosrizwan.com. root.centosrizwan.com. (
                              2         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
@       IN      NS      centosrizwan.com.
@       IN      A       192.168.8.100
@       IN      MX 0    192.168.8.100
mail    IN      A       192.168.8.100
www     IN      A       192.168.8.100
php     IN      A       192.168.8.100
wordpress       IN      A       192.168.8.100
phpmyadmin      IN      A       192.168.8.100

db.ipaddr

sudo vi /var/named/db.(your-ip)

;
; BIND reverse data file for local loopback interface
;
$TTL    604800
@       IN      SOA     centosrizwan.com. root.centosrizwan.com. (
                              1         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
@       IN      NS      centosrizwan.com.
100     IN      PTR     centosrizwan.com.
100     IN      PTR     www.centosrizwan.com.
100     IN      PTR     mail.centosrizwan.com.
100     IN      PTR     php.centosrizwan.com.
100     IN      PTR     wordpress.centosrizwan.com.
100     IN      PTR     phpmyadmin.centosrizwan.com.

Edit Resolv File

sudo vi /etc/resolv.conf

search centosrizwan.com    ## your domain
nameserver 192.168.8.100   ## your ip address
nameserver 192.168.8.1     ## your gateway

Enable and Restart DNS Service

sudo systemctl start named
sudo systemctl enable named

Add DNS service to Firewalld

sudo firewall-cmd --add-service=dns --permanent
sudo firewall-cmd --reload