A domain Name System is an internet service used to resolve a domain name to IP Address and vice versa. This DNS service relieves us from remembering IP addresses to reach any services over the internet or intranet.
Here, we will see how to set up DNS server on Ubuntu 22.04 / Ubuntu 20.04.
Set up Environment
Let us create a DNS server for the holhol24.local domain. You may also change it as per your requirement.
Domain Name: holhol24.local
DNS Server Name: ns.holhol24.local
IP Address: 192.168.0.10
Additionally, you need to ensure sure the DNS server has a static IP address.
READ: How to configure static ip address in Ubuntu 22.04/20.04
Install DNS Server
First, update the repository index.
sudo apt update
The package name of the DNS server in the Ubuntu operating system is bind9. It is available in the base OS repository. So, you can use the apt command to install the bind9 package along with other utility packages.
sudo apt install -y bind9 bind9-utils
Creating DNS Zones and Zone Files
Creating DNS Zones
The /etc/bind/ is the configuration directory for the DNS server that holds configuration files and zone files. The global configuration file for DNS server is /etc/bind/named.conf.
For the zone creations, use the /etc/bind/named.conf.local file instead of the global configuration file.
Let us begin by creating DNS zones for your domain.
sudo nano /etc/bind/named.conf.local
Creating Forward Zone
The following is the forward zone entry for the holhol24.local domain in the named.conf.local file. This forward zone translates a fully qualified domain name (FQDN) into an IP address.
zone "holhol24.local" IN { // Domain name
type master; // Primary DNS
file "/etc/bind/holhol24.local.db"; // Forward Zone file
allow-update { none; }; // Since this is the primary DNS, it should be none.
};
Creating Reverse Zone
The following is for the reverse name resolution zone in the named.conf.local file. This forward zone translates an IP address into a fully qualified domain name (FQDN).
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/r.holhol24.local.db"; // Reverse lookup file
allow-update { none; }; // Since this is the primary DNS, it should be none.
};
Creating Zone Files
Once you have created DNS zones, create DNS zone files for the forward and reverse zones.
Creating Forward Zone File
Create a zone file /etc/bind/holhol24.local.db for the forward zone.
sudo nano /etc/bind/holhol24.local.db
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 (.).
Whenever you change any records in the zone file, update the serial number +1 with the current number.
$TTL 86400
@ IN SOA ns.holhol24.local. root.holhol24.local. (
200101 ; Serial
21600 ; Refresh
3600 ; Retry
604800 ; Expire
86400 ) ; Negative Cache TTL
;
;Name Server Information
@ IN NS ns.holhol24.local.
;IP address of Name Server
ns IN A 192.168.0.10
;Mail Exchanger
@ IN MX 10 mail.holhol24.local.
;A – Record HostName To Ip Address
www IN A 192.168.0.101
mail IN A 192.168.0.102
;CNAME record
ftp IN CNAME www.itgeek.local.
Creating Reverse Zone File
Create a zone file /etc/bind/r.holhol24.local.db for the reverse zone.
sudo nano /etc/bind/r.holhol24.local.db
Update the content as shown below.
PTR – Pointer
SOA – Start of Authority
Whenever you change any records in the lookup file, update the serial number +1 with the current number.
$TTL 86400
@ IN SOA ns.holhol24.local. root.holhol24.local. (
200101 ; Serial
21600 ; Refresh
3600 ; Retry
604800 ; Expire
86400 ) ; Negative Cache TTL
;
;Name Server Information
@ IN NS ns.holhol24.local.
;Reverse lookup for Name Server
10 IN PTR ns.holhol24.local.
;PTR Record IP address to HostName
101 IN PTR www.holhol24.local.
102 IN PTR mail.holhol24.local.
Validating DNS Syntax
Use the named-checkconf command to check the syntax of DNS configuration 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.
Validating Forward Zone
sudo named-checkzone holhol24.local /etc/bind/holhol24.local.db
Output:
zone holhol24.local/IN: loaded serial 200101 OK
Validating Reverse Zone
sudo named-checkzone 0.168.192.in-addr.arpa /etc/bind/r.holhol24.local.db
Output:
zone 0.168.192.in-addr.arpa/IN: loaded serial 200101 OK
Finally, reload both the configuration file and zones. You may also use the same command whenever you change zone and zone files.
sudo rndc reload
Verify DNS Server
Use the dig command to verify the DNS server by looking up records.
dig www.holhol24.local @192.168.0.10
Output:
; > DiG 9.18.1-1ubuntu1-Ubuntu > www.holhol24.local @192.168.0.10 ;; global options: +cmd ;; Got answer: ;; WARNING: .local is reserved for Multicast DNS ;; You are currently testing what happens when an mDNS query is leaked to DNS ;; ->>HEADERwww.holhol24.local. 86400 IN A 192.168.0.101 ;; Query time: 0 msec ;; SERVER: 192.168.0.10#53(192.168.0.10) (UDP) ;; WHEN: Mon May 30 11:28:51 EDT 2022 ;; MSG SIZE rcvd: 90
Confirm the reverse lookup with the dig command.
dig -x 192.168.0.101 @192.168.0.10
Output:
; > DiG 9.18.1-1ubuntu1-Ubuntu > -x 192.168.0.101 @192.168.0.10 ;; global options: +cmd ;; Got answer: ;; ->>HEADER101.0.168.192.in-addr.arpa. 86400 IN PTR www.holhol24.local. ;; Query time: 0 msec ;; SERVER: 192.168.0.10#53(192.168.0.10) (UDP) ;; WHEN: Mon May 30 11:33:24 EDT 2022 ;; MSG SIZE rcvd: 114
This result confirms that both the forward and reverse zone are working fine.
Conclusion
That’s All. I hope you have learned how to set up DNS server on Ubuntu 22.04 / Ubuntu 20.04. In the next article, we will configure the slave DNS server on Ubuntu.
