Lesson 5: Network Configuration and Troubleshooting

Every device on a network needs an IP address (like a house number). An IPv4 address looks like 192.168.0.10, often paired with a subnet mask like 255.255.255.0. The mask defines which part of the address is the network vs host. For example, with 255.255.255.0, devices 192.168.0.1–254 are on the same LAN. Subnetting creates smaller networks (subnets) to organize larger networks efficiently. In practice, sysadmins might encounter both IPv4 and IPv6 addresses, but for most exams, focus on IPv4 and how to calculate simple subnets (e.g. /24 means 255.255.255.0).

To connect to a network, a computer needs an IP, gateway, and DNS servers. On Windows, you use Network Connections settings: IPv4 properties allow you to enter a static IP, mask, gateway, and DNS. On Linux, you might edit a config file (like /etc/network/interfaces) or use nmcli (NetworkManager) commands. For example, sudo nano /etc/network/interfaces could contain address 10.0.0.10/24 and gateway 10.0.0.1. Many networks use DHCP, where a router assigns IPs automatically. In that case, the setting is on "Obtain an IP address automatically" (Windows) or dhclient on Linux.