Configure Hostname Resolution | RHCSA

Introduction

In this challenge, you will learn how to configure hostname resolution on a Linux system. Proper hostname resolution is essential for network communication. You will practice setting up static hostname resolution using the /etc/hosts file and then configure the system to use a DNS server for dynamic resolution.

Configure Static Hostname Resolution

Your first task is to configure static hostname resolution. This method is useful for small networks or for overriding public DNS entries. You will edit the /etc/hosts file to map an IP address to a hostname.

Tasks

Configure static hostname resolution for myhost.example.com.

Requirements

Edit the /etc/hosts file to map the IP address 192.168.1.100 to the hostname myhost.example.com.
Verify that the hostname myhost.example.com correctly resolves to 192.168.1.100.

Hints

Use a command-line text editor like nano or vi with sudo privileges to edit /etc/hosts.
The getent hosts <hostname> command is a reliable way to test name resolution.

Example

After correctly configuring the /etc/hosts file, the output of the getent command should be:

$ getent hosts myhost.example.com
192.168.1.100   myhost.example.com

Configure Dynamic Hostname Resolution

Now, you will switch from static to dynamic (DNS-based) resolution. For this exercise, a simple DNS server has been pre-configured and is running on your local machine (127.0.0.1). Your task is to disable the static entry and configure your system to use this DNS server.

Tasks

Disable the static hostname entry from the previous step.
Configure the system to use the local DNS server.

Requirements

The static entry for myhost.example.com in /etc/hosts must be disabled. You can do this by deleting the line or commenting it out with a # at the beginning.
Configure the system's DNS client to use the nameserver at 127.0.0.1.
Verify the new configuration using the dig command.

Hints

The primary file for configuring a DNS client is /etc/resolv.conf.
The dig command is a powerful tool for querying DNS servers.

Example

After correctly configuring the resolver and disabling the static host entry, the dig command should produce output similar to this, showing the resolution from the server:

$ dig myhost.example.com

; <<>> DiG 9.16.23-RH <<>> myhost.example.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 58851
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;myhost.example.com.            IN      A

;; AUTHORITY SECTION:
example.com.            5       IN      SOA     ns.icann.org. noc.dns.icann.org. 2025011748 7200 3600 1209600 3600

;; Query time: 62 msec
;; SERVER: 100.100.2.136#53(100.100.2.136)
;; WHEN: Fri Aug 15 17:18:27 CST 2025
;; MSG SIZE  rcvd: 101

Summary

In this challenge, you learned how to manage basic hostname resolution. You practiced configuring static resolution by editing the /etc/hosts file and then switched to dynamic resolution by configuring the system as a DNS client via the /etc/resolv.conf file. These are fundamental skills for network configuration and system administration on Linux.