Testing DNS Resolution

30 minutes
  • 2 Learning Objectives

About this Hands-on Lab

A Linux system administrator is expected to know how to configure a system’s DNS settings. Nearly all modern Linux distributions use NetworkManager to handle a host’s DNS settings. In this learning activity, we will utilize the `nmcli` utility to configure our DNS resolution.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Review current DNS configuration.

You have successfully been able to ping the gateway for the network. Now you need to verify that the system is capable of communicating with the network. Do the following to complete the review:

  1. Run the host command to see if your system can resolve hostnames to IP addresses.
  2. Check to see what DNS server entries you have in the /etc/resolv.conf file.
    1. Review your network connections via the ip and the nmcli commands.
  3. Your default connection should be highlighted with the name System ens5. (Hardware changes may result in the name of the active interface changing, proceed with the lab using the name shown in place of ‘ens5’.)
  4. Use the nmcli command again to review your DNS IP settings.
Configure your system to use your network’s DNS.
  1. Use the nmcli command to modify the system’s default connection to use the network’s DNS server.
  2. Verify the settings by using the nmcli command, and by checking the /etc/resolv.conf file.
  3. Re-activate the network connection to have our /etc/resolv.confshow the new DNS server.
  4. Verify your settings once more.
  5. Attempt to resolve a hostname to an IP address.

Additional Resources

You just started a new job where you will be managing a server for a small business. After you take inventory of the equipment, you notice that one of the servers on the local network is not configured to use DNS. After you ask your fellow employees about it, they say that the system in question has never been able to access remote sites for updates. You have determined that the server can not get updates because it can not resolve the hostnames for the update servers to the IP addresses. You sit down to correct this issue, with the help of the nmcli command-line tool.

DNS Server IP Address:

What are Hands-on Labs

Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.

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