Troubleshooting·LPIC-2
Reading a DNS answer: NXDOMAIN and REFUSED
dig +short returning nothing looks the same whether the name does not exist, the server refuses to answer, or the server is not there. The status line distinguishes them, and this guide produces all three against a real server so the difference is visible rather than described.
202: DNS Guide 9 of 29 Intermediate
- OSUbuntu 26.04 LTS
- Kernel7.0.0-30-generic
- systemd259
- Block devicesone 50 GB disk
- TimeAbout 14 min
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| LPIC2-A01 | 192.168.0.78 | Ubuntu 26.04 LTS | Primary service host - BIND, Apache, Samba, Postfix. Topic 204 RAID runs on loop devices; this machine has no spare disk | 2 Core | 4 GB | 50 GB |
| LPIC2-C01 | 192.168.0.80 | Ubuntu 26.04 LTS | Client - resolves, mounts and connects, so every service is proven from a machine that is not running it | 2 Core | 4 GB | 50 GB |
This guide includes
Use this because dig +short returning nothing looks identical in three different situations. This matters because the name not existing, the server refusing, and nothing listening are three separate faults wearing one appearance.
- querying a name that does not exist
- querying a name outside this server's zone, for the same empty output
- querying when nothing is there at all, and telling all three apart
Before you start
- a-dns-zone-proved-from-a-client
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A name that does not exist
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A name outside this server's zone
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And when nothing is there at all