Networking · Lesson 17 of 26 · 8 minutes

DNS hosts comparison

Compare resolver and hosts file context.

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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 resolver
Run cat /etc/resolv.conf.
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/resolv.conf
```
Remember: Reading a source file should precede changing it; avoid printing real secrets.
2
Read hosts
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
Find nameserver
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

Junior operators build confidence by gathering evidence before changing systems.

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

$ cat /etc/resolv.conf

nameserver 192.0.2.53
# fake resolver for training only

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

Apply it elsewhere

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

Keep the momentum.

Complete the lab, then explain and apply the pattern.

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