DevOps Garfield

Cloud Club Topics - Domain Name Servers ( DNS )

Name servers

Creating servers is great and memorizing IP addresses on a small network is OK. But, names are a lot easier to remember than IP address, especially on a large netowrk ( eg. the internet ).
The original way to name servers is to use a file ( /etc/hosts )

Hands-On naming servers

Edit the /etc/hosts file on your server(s). It should look like the following

27.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1        localhost localhost.localdomain localhost6 localhost6.localdomain6

Add the following content at the bottom - ( replace the webserver IPs and names + the LB IP and name )

<webserver_1_IP>  <webserver_1_name>.cloudclub.edu
<webserver_2_IP>  <webserver_2_name>.cloudclub.edu
<LB_IP>           <LB_name>.cloudclub.edu

View the websites with curl

curl http://<webserver_1_name>.cloudclub.edu/
curl http://<webserver_2_name>.cloudclub.edu/
curl http://<LB_name>.cloudclub.edu/

Understanding DNS

DNS is the Domain Name System
1. Examples of DNS software:

Name	Supported OS
Bind 9	Linux, Windows Server 2012+, Windows 10+
DNSmasq	Linux, Mac

Hands-on installing a DNS server

Create a Rocky Linux server ( if you don't already have one )
1. Assign an IP address from your range
2. Install bind9 ( dns server software )
```
sudo dnf install bind bind-utils -y
sudo systemctl enable --now bind
```

Hands-on configure a DNS server

Edit the config file ( /etc/named.conf )

Configure main options

  options {
            listen-on port 53 { any; };
            listen-on-v6 port 53 { any; };
            directory       "/var/named";
            ...
            allow-query { any; };
        };

Define you domain

zone "cloudclub.edu" {
        type master;
        file "/var/named/cloudclub.edu.db";
       };

Create the directory if it doesn't already exist ( it does on our server )
```
sudo mkdir -p /var/named
```

Create the zone file ( /var/named/cloudclub.edu.db )

$ttl 38400
cloudclub.edu.     IN      SOA     dns.cloudclub.edu. admin.cloudclub.edu. (
                        1611368586
                        10800
                        3600
                        604800
                        38400 )
cloudclub.edu.          IN      NS      dns.cloudclub.edu.
dns.cloudclub.edu.      IN      A       192.168.1.11
repo.cloudclub.edu.     IN      A       192.168.1.11

Enable/start bind service
```
sudo sytemctl enable --now named
```
Check your configuration doesn't have errors
```
sudo named-checkconf /etc/named.conf
```
Check that you get a result from a basic query of your domain
```
sudo dig @localhost cloudclub.edu
```

Open the DNS port/service in the firewall

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

Test query your DNS server for one of the addresses you added

dig @192.168.1.11 repo.cloudclub.edu


; <<>> DiG 9.16.23-RH <<>> repo.cloudclub.edu
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 394
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: 81331712b590bb610100000068085e3f33d592afa55f8a0c (good)
;; QUESTION SECTION:
;repo.cloudclub.edu.		IN	A

;; ANSWER SECTION:
repo.cloudclub.edu.	38400	IN	A	192.168.1.11

;; Query time: 2 msec
;; SERVER: 192.168.1.11#53(192.168.1.11)
;; WHEN: Tue Apr 22 20:27:59 PDT 2025
;; MSG SIZE  rcvd: 91

Request the short result with only the answer

dig +short @192.168.1.11 repo.cloudclub.edu

192.168.1.11

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