Troubleshooting·LPIC-1
Name resolution, and diagnosing in the right order
Objective 109.4 is client-side DNS and 109.3 is basic troubleshooting, and they belong together: most "the network is down" reports are name resolution. This guide shows which file decides the order sources are tried, proves it by making /etc/hosts override an answer DNS was already giving, and then runs the three checks that locate a fault in the right layer - including one that genuinely failed.
102: Networking Fundamentals Guide 22 of 33 Beginner
- PlatformsUbuntu 26.04 LTS + AlmaLinux 10.2
- TimeAbout 19 min
- RPM packagingrpm 4.19.1.1, dnf 4.20.0
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| LPIC1-A01 | 192.168.0.76 | Ubuntu 26.04 LTS | Debian-family host - dpkg and apt, which objective 102.4 names | 2 Core | 4 GB | 50 GB |
| LPIC1-B01 | 192.168.0.77 | AlmaLinux 10.2 | RPM-family host - rpm and dnf, which objective 102.5 names | 2 Core | 4 GB | 50 GB |
This guide includes
Use this for client-side DNS and basic troubleshooting together. This matters because files really do beat DNS - and checking in the right order narrows the fault fastest.
- finding the file that decides the order, before any resolver runs
- proving that files beat DNS, on a name that already resolved
- running three checks in the order that narrows fastest
Before you start
- addresses-routes-and-what-the-mask-decides
-
The file that decides the order
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Proving that files really do beat DNS
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Three checks, in the order that narrows fastest