Networking · Lesson 24 of 26 · 8 minutes

Local name resolution

Compare hostname, hosts-file, and resolver configuration evidence.

Open the lab Course map

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learner@clairos:~ $

↑ history · Tab complete · Ctrl+C cancel · Esc, Tab to leaveExit 0

Your objectives

Hints are always available. Wrong turns never cost XP.

1
Read the local hostname
Run hostname.
Hint & worked example
Read the simulated host name.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
hostname
```
Remember: A name helps orient an operator but is not proof of network reachability.
2
Read local host mappings
Run cat /etc/hosts.
Hint & worked example
Read one or more files to standard output without editing their contents.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
cat /etc/hosts
```
Remember: Reading a source file should precede changing it; avoid printing real secrets.
3
Read the configured resolver
Run grep nameserver /etc/resolv.conf.
Hint & worked example
Select input lines that match a pattern; -i ignores case, -n adds line numbers, and -v inverts selection.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
grep nameserver /etc/resolv.conf
```
Remember: No matches is exit status 1, which is different from a malformed invocation.

Understand the pattern

Understanding local name-resolution inputs helps operators explain what they know before they change anything.

hostname: Read the simulated host name.
A name helps orient an operator but is not proof of network reachability.
cat: Read one or more files to standard output without editing their contents.
Reading a source file should precede changing it; avoid printing real secrets.
grep: Select input lines that match a pattern; -i ignores case, -n adds line numbers, and -v inverts selection.
No matches is exit status 1, which is different from a malformed invocation.

Worked example and expected result

$ hostname

clairos-learn-lab

Exit status: 0. The command completed successfully in the training fixture.

$ cat /etc/hosts

127.0.0.1 localhost
10.20.30.40 clairos-learn-lab

Exit status: 0. The command completed successfully in the training fixture.

$ grep nameserver /etc/resolv.conf

nameserver 192.0.2.53

Exit status: 0. The command completed successfully in the training fixture.

Try a variation

Repeat this workflow in the sandbox with a different scratch filename. Keep the system fixtures unchanged and compare the observed output with your expectation before moving on.

Explain it

In “Local name resolution”, which interpretation is safe?A successful first check guarantees that every dependent service is healthy.Reading a source file should precede changing it; avoid printing real secrets.A command appearing in history proves it completed successfully.

Apply it elsewhere

Before adapting the cat workflow from “Local name resolution” to another server, what should you do?Confirm the current directory, target identity, permissions, and the installed command behavior first.Paste the training paths unchanged into production.Skip output inspection whenever the command is familiar.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

Next: Route listener firewall correlation Try an incident drill

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