How to configure Caching DNS Server in Ubuntu
To configure Caching DNS Server in Ubuntu
Domain Name System is a naming device that maps the IP addresses and fully qualified domain names to one another. The Internet maintains two main namespaces - the domain name format and the Internet Protocol (IP) address format. The DNS controls the domain name hierarchy and helps in transforming the name server and IP address. The server that caches the DNS entries for a domain is called as DNS name server. The default port number for DNS is 53. This article explains the installation and configuration of DNS Server .
1. Installation of DNS Server
DNS server information:
IP Address: 192.168.5.230
Hostname: dns.linuxhelpedu.com
Install the DNS bind Packages by executing the below command.
root@dns:~# apt-get install bind9*
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting ' bind9-host' for glob ' bind9*'
.
.
.
wrote key file " /etc/bind/rndc.key"
Setting up bind9-doc (1:9.10.3.dfsg.P4-8ubuntu1) ...
Setting up bind9-dyndb-ldap (8.0-4) ...
Processing triggers for libc-bin (2.23-0ubuntu3) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for systemd (229-4ubuntu4) ...
Processing triggers for ufw (0.35-0ubuntu2) ...
Now the installation of bind packages is successfully completed.
2. DNS Cache Server Setup
Using nano editor, go to the directory ' /etc/bind' and edit the file ' named.conf.options' .
root@dns:~# nano /etc/bind/named.conf.options
Remove ' //' in front of forwarders tag and replace 0.0.0.0 to 8.8.8.8 as shown below.
forwarders { 8.8.8.8 }
Save and quit the file.
After editing, restart bind service to apply the changes.
root@dns:~# service bind9 restart
3. Master DNS Server Setup
Open /etc/bind/named.conf file using nano editor.
root@dns:~# nano /etc/bind/named.conf
The configuration file must contains following lines. If it is not available then type it inside the configuration file.
Include “ /etc/bind/named.conf.option” Include “ /etc/bind/named.conf.local” Include “ /etc/bind/named.conf.default-zones”
And then save and quit the file.
Next go to the configuration file inside ' /etc/bind' .
root@dns:~# nano /etc/bind/named.conf.local
And then declare the forward and reverse zone file and its path as follows.
zone " linuxhelpedu.com" { type master file " /etc/bind/forward.linuxhelpedu" allow-transfer { 192.168.5.230 } also-notify { 192.168.5.230 } } zone " 5.168.192.in-addr.arpa" { type master file " /etc/bind/reverse.linuxhelpedu" allow-transfer { 192.168.5.230 } also-notify { 192.168.5.230 } }
Inside ' /etc/bind/' directory create forward zone file.
root@dns:~# nano /etc/bind/forward.linuxhelpedu
Type the following configuration inside the forward zone file.
$TTL 86400 @ IN SOA dns.linuxhelpedu.com. root.linuxhelpedu.com. ( 2011071002 Serial 3600 Refresh 1800 Retry 604800 Expire 86400 Minimum TTL ) @ IN NS dns.linuxhelpedu.com. @ IN A 192.168.5.230 @ IN A 192.168.5.233 dns IN A 192.168.5.230 client IN A 192.168.5.233
In the same way, inside ' /etc/bind/' directory create reverse zone file .
root@dns:~# nano /etc/bind/reverse.linuxhelpedu
Type the following configuration inside the reverse zone file.
$TTL 86400 @ IN SOA dns.linuxhelpedu.com. root.linuxhelpedu.com. ( 2011071002 Serial 3600 Refresh 1800 Retry 604800 Expire 86400 Minimum TTL ) @ IN NS dns.linuxhelpedu.com. @ IN PTR linuxhelpedu.com. dns IN A 192.168.5.230 client IN A 192.168.5.233 230 IN PTR dns.linuxhelpedu.com. 233 IN PTR client.linuxhelpedu.com.
Syntax validation
Check ' named.conf' and ' named.conf.local' file for any syntax error.
root@dns:~# named-checkconf /etc/bind/named.conf
root@dns:~# named-checkconf /etc/bind/named.conf.local
And then check forward zone and reverse zone by executing the following command.
root@dns:~# named-checkzone linuxhelpedu.com /etc/bind/forward.linuxhelpedu zone linuxhelpedu.com/IN: loaded serial 2011071002 OK root@dns:~# named-checkzone linuxhelpedu.com /etc/bind/reverse.linuxhelpedu zone linuxhelpedu.com/IN: loaded serial 2011071002 OK
Restart the ' bind' service by executing the following command.
root@dns:~# service bind9 restart
Configuring network interface
Go to the ' /etc/network/' path, and edit the ' interface' configuration file.
root@dns:~# nano /etc/network/interfaces
Add ' dns-nameserver' and ' dns-search' as follows.
auto ens33 iface ens33 inet static address 192.168.5.230 netmask 255.255.255.0 network 192.168.5.0 broadcast 192.168.5.255 gateway 192.168.5.1 dns-nameservers 192.168.5.230 dns-search linuxhelpedu.com
Then save and quit the file. Restart the network service.
Test DNS server
After rebooting, test the dns server using ' dig’ and ' nslookup' command.
root@dns:~# dig dns.linuxhelpedu.com
< < > > DiG 9.10.3-P4-Ubuntu < < > > dns.linuxhelpedu.com
global options: +cmd
Got answer:
-> > HEADER< < -opcode: QUERY, status: NOERROR, id: 32897
flags: qr aa rd ra QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1
OPT PSEUDOSECTION:
EDNS: version: 0, flags: udp: 4096
QUESTION SECTION:
dns.linuxhelpedu.com. IN A
ANSWER SECTION:
dns.linuxhelpedu.com. 86400 IN A 192.168.5.230
AUTHORITY SECTION:
linuxhelpedu.com. 86400 IN NS dns.linuxhelpedu.com.
Query time: 0 msec
SERVER: 192.168.5.230#53(192.168.5.230)
WHEN: Fri Apr 29 15:21:37 IST 2016
MSG SIZE rcvd: 79
root@dns:~# nslookup dns.linuxhelpedu.com
Server: 192.168.5.230
Address: 192.168.5.230#53
Name: dns.linuxhelpedu.com
Address: 192.168.5.230
root@dns:~#
Now we have configured and tested the Server side DNS.
For further information about the ' dig’ command visit,
https://www.linuxhelp.com/dig-command-query-dns/
For further information about the ' nslookup' command visit,
https://www.linuxhelp.com/troubleshoot-dns-using-nslookup/
4. Client Machine Setup
Set ' nameserver' and ' search' .
Nameserver is dns server ip
Search is dns server host name.
To check ' hostname' , run the following command.
user1@client:~$ hostname
client.linuxhelpedu.com.
Edit ' /etc/resolv.conf' file using nano editor.
user1@client:~$ nano /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 192.168.5.230
search linuxhelpedu.com
Restart network service or reboot client system to apply the changes.
Test Dns server in client machine
Test dns server from client machine using ' dig' and ' nslookup' .
user1@client:~$ dig dns.linuxhelpedu.com < < > > DiG 9.10.3-P4-Ubuntu < < > > dns.linuxhelpedu.com global options: +cmd Got answer: -> > HEADER< < -opcode: QUERY, status: NOERROR, id: 42737 flags: qr aa rd ra QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1 OPT PSEUDOSECTION: EDNS: version: 0, flags: udp: 4096 QUESTION SECTION: dns.linuxhelpedu.com. IN A ANSWER SECTION: dns.linuxhelpedu.com. 86400 IN A 192.168.5.230 AUTHORITY SECTION: linuxhelpedu.com. 86400 IN NS dns.linuxhelpedu.com. Query time: 1066 msec SERVER: 192.168.5.230#53(192.168.5.230) WHEN: Sat Apr 30 14:12:59 IST 2016 MSG SIZE rcvd: 79 user1@client:~$ nslookup dns.linuxhelpedu.com Server: 192.168.5.230 Address: 192.168.5.230#53 Name: dns.linuxhelpedu.com Address: 192.168.5.230
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