How To Configure DNS Server On Ubuntu 18.04 / Ubuntu 16.04

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Configure DNS Server On Ubuntu 18.04
Configure DNS Server On Ubuntu 18.04

Domain Name System (DNS) is the root of the internet that translates the domain name to IP Address and vice versa. BIND9 (Berkeley Internet Name Domain) package provides the functionality of the name to IP conversion.

This post will guide you to configure DNS server on Ubuntu 18.04  / Ubuntu 16.04.

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Environment

Domain Name: itzgeek.local
ns1.itzgeek.local192.168.0.10Master DNS Server

Setup DNS Server on Ubuntu 18.04 / Ubuntu 16.04

Prerequisites

Update the repository index.

sudo apt update

Make sure the DNS server has a static IP address.

READ: How to configure static IP address in Ubuntu 18.04 / Ubuntu 16.04 using ifupdown

If you are using Netplan – a new network tool for configuring networking in Ubuntu 18.04, then.

READ: How To Configure Static IP Address in Ubuntu 18.04 using Netplan

Install DNS Server

The package name for the DNS server on Ubuntu is bind9 and is available in the base repository. Use the apt command to install the bind9 package.

sudo apt install -y bind9 bind9utils bind9-doc dnsutils

Configure DNS Server

The /etc/bind/ directory is the main configuration directory of the DNS server, and it holds configuration files and zone lookup files.

Global configuration file is /etc/bind/named.conf. You should not use this file for your local DNS zone rather you can use /etc/bind/named.conf.local file.

Create Zones

Let us begin by creating a forward zone for your domain.

sudo nano /etc/bind/named.conf.local
Forward Zone

The following is the forward zone entry for the itzgeek.local domain in the named.conf.local file.

zone "itzgeek.local" IN { // Domain name
    
      type master; // Primary DNS

     file "/etc/bind/forward.itzgeek.local.db"; // Forward lookup file

     allow-update { none; }; // Since this is the primary DNS, it should be none.

};
Reverse Zone

The following entries are for the reverse zone in the named.conf.local file.

zone "0.168.192.in-addr.arpa" IN { //Reverse lookup name, should match your network in reverse order

     type master; // Primary DNS

     file "/etc/bind/reverse.itzgeek.local.db"; //Reverse lookup file

     allow-update { none; }; //Since this is the primary DNS, it should be none.

};

Create Zone lookup file

Once you create zones, you can go ahead and create zone data files that hold DNS records for the forward zone and reverse zone.

Forward Zone lookup file

Copy the sample entries to zone file called forward.itzgeek.local.db for the forward zone under /etc/bind directory.

Record types in the zone file,

SOA – Start of Authority
NS – Name Server
A – A record
MX – Mail for Exchange
CN – Canonical Name

Domain names should end with a dot (.).

sudo cp /etc/bind/db.local /etc/bind/forward.itzgeek.local.db

Edit the zone.

sudo nano /etc/bind/forward.itzgeek.local.db

Update the content shown below.

Whenever you change any records in the lookup file, make sure you update the serial number to some random number, higher than current.
$TTL    604800
@       IN      SOA     ns1.itzgeek.local. root.itzgeek.local. (
                              3         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
;@      IN      NS      localhost.
;@      IN      A       127.0.0.1
;@      IN      AAAA    ::1

;Name Server Information

@        IN      NS      ns1.itzgeek.local.

;IP address of Name Server

ns1     IN      A       192.168.0.10

;Mail Exchanger

itzgeek.local.   IN     MX   10   mail.itzgeek.local.

;A – Record HostName To Ip Address

www     IN       A      192.168.0.100
mail    IN       A      192.168.0.150

;CNAME record

ftp     IN      CNAME   www.itgeek.local.
Reverse Zone lookup file

Copy the sample entries to the zone file called reverse.itzgeek.local.db for the reverse zone under /etc/bind directory and create reverse pointers for the above forward zone records.

PTR – Pointer
SOA – Start of Authority

sudo cp /etc/bind/db.127 /etc/bind/reverse.itzgeek.local.db

Edit the reverse zone file.

sudo nano /etc/bind/reverse.itzgeek.local.db

Update the content shown below.

Whenever you change any DNS records in the lookup file, make sure to update the serial number to some random number, higher than the current one.
$TTL    604800
@       IN      SOA     itzgeek.local. root.itzgeek.local. (
                              3         ; Serial
                         604800         ; Refresh
                          86400         ; Retry
                        2419200         ; Expire
                         604800 )       ; Negative Cache TTL
;
;@      IN      NS      localhost.
;1.0.0  IN      PTR     localhost.

;Name Server Information

@       IN      NS     ns1.itzgeek.local.

;Reverse lookup for Name Server

10      IN      PTR    ns1.itzgeek.local.

;PTR Record IP address to HostName

100     IN      PTR    www.itzgeek.local.
150     IN      PTR    mail.itzgeek.local.

Check BIND Configuration Syntax

Use named-checkconf command to check the syntax and named.conf* files for any errors.

sudo named-checkconf

Command will return to the shell if there are no errors.

Also, you can use named-checkzone to check the syntax errors in zone files.

Forward zone

sudo named-checkzone itzgeek.local /etc/bind/forward.itzgeek.local.db

Output:

zone itzgeek.local/IN: loaded serial 3
OK

Reverse zone

named-checkzone 0.168.192.in-addr.arpa /etc/bind/reverse.itzgeek.local.db

Output:

zone 0.168.192.in-addr.arpa/IN: loaded serial 3
OK

Restart bind service.

sudo systemctl restart bind9

Enable it on system startup.

sudo systemctl enable bind9

Check the status of the bind9 service.

sudo systemctl status bind9

DNS Record Update

Whenever you change a DNS record, do not forget to change the serial number in the zone file and reload the zone.

Change itzgeek.local & 0.168.192.in-addr.arpa with your zone names.

### Forward Zone ###

sudo rndc reload itzgeek.local 

### Reverse Zone ###

sudo rndc reload 0.168.192.in-addr.arpa

Verify DNS Server

Go to any client machine and add our new DNS server IP Address in /etc/resolv.conf file.

sudo nano /etc/resolv.conf

Make an entry like below.

nameserver 192.168.0.10

OR

Read the below tutorial to set DNS server IP in Linux.

READ: How to Set DNS IP address in CentOS / Fedora

READ: How to Set DNS IP address in Ubuntu / Debian – ifupdown

READ: How To Set DNS IP Address in Ubuntu 18.04 – Netplan

Use the dig command to check the forward zone.

dig www.itzgeek.local

If you get command not found, then install the bind-utils package.

Output:

; <<>> DiG 9.10.3-P4-Ubuntu <<>> www.itzgeek.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18022
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.itzgeek.local.             IN      A

;; ANSWER SECTION:
www.itzgeek.local.      604800  IN      A       192.168.0.100

;; AUTHORITY SECTION:
itzgeek.local.          604800  IN      NS      ns1.itzgeek.local.

;; ADDITIONAL SECTION:
ns1.itzgeek.local.      604800  IN      A       192.168.0.10

;; Query time: 0 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Mon Dec 30 12:42:18 EST 2019
;; MSG SIZE  rcvd: 96

The DNS server’s answer for the forward lookup: 192.168.0.100 as IP address for www.itzgeek.local.

Confirm the reverse lookup with dig command.

dig -x 192.168.0.100

Output:

; <<>> DiG 9.10.3-P4-Ubuntu <<>> -x 192.168.0.100
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37122
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;100.0.168.192.in-addr.arpa.    IN      PTR

;; ANSWER SECTION:
100.0.168.192.in-addr.arpa. 604800 IN   PTR     www.itzgeek.local.

;; AUTHORITY SECTION:
0.168.192.in-addr.arpa. 604800  IN      NS      ns1.itzgeek.local.

;; ADDITIONAL SECTION:
ns1.itzgeek.local.      604800  IN      A       192.168.0.10

;; Query time: 0 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Mon Dec 30 12:43:20 EST 2019
;; MSG SIZE  rcvd: 120

The DNS server’s answer for reverse lookup: www.itzgeek.local as a name for 192.168.0.100.

This result confirms that both zone lookups are working fine.

Conclusion

That’s All. You now have successfully configured DNS server on Ubuntu 18.04  / Ubuntu 16.04 as the master server. In our next post, we will configure a slave DNS server on Ubuntu 18.04  / Ubuntu 16.04.

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