Addresses, links, and where the configuration lives
Networking is a quarter of the LFCS exam and it starts here: reading the addresses a machine has, then finding the file that will still say so after a reboot. Ubuntu and RHEL disagree completely about that second part, so this guide shows both.
Networking Guide 22 of 38 Beginner
- PlatformsUbuntu 26.04 LTS + AlmaLinux 10.2
- LVM2.03.31 (Ubuntu) / 2.03.36 (AlmaLinux)
- nftables1.1.6 (Ubuntu) / 1.1.5 (AlmaLinux)
- TimeAbout 16 min
Ubuntu 26.04 with netplan rendering to systemd-networkd; RHEL 10 with NetworkManager and no netplan installed at all. ip is iproute2 and identical on both. ifconfig, route and netstat are deprecated and absent from a minimal install of either - do not learn them for this exam.
- Firewallufw 0.36.2 enabled but reporting inactive / firewalld active
- Network confignetplan + systemd-networkd / NetworkManager 1.56.0
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| LFCS-A01 | 192.168.0.70 | Ubuntu 26.04 LTS | Primary host - most guides run only here | 2 Core | 4 GB | 50 GB |
| LFCS-C01 | 192.168.0.72 | AlmaLinux 10.2 | The other distribution - dnf, firewalld and NetworkManager | 2 Core | 4 GB | 50 GB |
This guide includes
Use this to open the networking quarter of the exam. This matters because reading the current address is not the same as knowing what comes back after a reboot - each family writes that down somewhere different.
- reading what the machine has right now, in summary and in full
- finding where Ubuntu writes it down, and which renderer does the work
- reading RHEL's connection profile for the same settings
- changing an address inside a network namespace, without risking the host
- taking it down, and proving the host itself never changed
Before you start
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What this machine has right now
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Where Ubuntu writes it down
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Which renderer is doing the work
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RHEL's side of the same question
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Changing an address without risking the host
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Taking it down, and proving nothing changed