By Emmett Dulaney

The Linux+ certification exam from CompTIA covers the topic of Linux networking fundamentals. The table shows the subtopics, weights, descriptions, and key knowledge areas for this topic.

Breakout of Domain 109
Subtopic Weight Description Key Areas
Fundamentals of Internet protocols 4 Demonstrate a proper understanding of TCP/IP Know networking fundamentals
Basic network configuration 4 Be able to view, change, and verify configuration settings on
clients and hosts
Manually and automatically configure network interfaces
Basic network troubleshooting 4 Be able to troubleshoot networking issues on clients and
hosts
Debug problems associated with the network configuration
Configure client side DNS 2 Be able to configure DNS on a client/host Modify the order in which name resolution is done

To adequately address these topics, focus on the following files, terms, and utilities: /etc/hostname, /etc/hosts, /etc/nsswitch.conf, /etc/resolv.conf, /etc/services, dig, ftp, host, hostname, ifconfig, ifdown, ifup, netstat, ping, route, telnet, tracepath, and traceroute.

Here are the top ten items to know as you study for this domain:

  1. IPv4 uses 32-bit addresses divided into four octets. The first octet identifies the class of address (A, B, C). The address can be public or private.

  2. The ifconfig utility can be used to see the current IP configuration of the network cards.

  3. The ping utility is an all-purpose tool for testing connectivity. It will send echo messages to a specified host to see if it can be reached. It can be used with the loopback address (127.0.0.1) to test internal configuration.

  4. Instead of using ping, one can use traceroute to see the route taken to reach a particular host.

  5. The route utility will display the routing table and allow you to configure it.

  6. The netstat utility will show the current status of ports — those that open, those that are listening, and so on.

  7. The name of the network host is configured in /etc/hostname and can be viewed with the hostname command.

  8. You can remotely log in to to another host with telnet, but it’s highly recommended that this utility no longer be used due to very weak security.

  9. Ftp servers can be used to transfer files from one host to another.

  10. DNS is used for resolving names to addresses. Utilities that can be used in conjunction with it include dig (for DNS lookup).