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LAB-NET-03 - DNS and Name Resolution

Query DNS directly and recognize when a hostname problem is different from a reachability problem.

NET Networking and Communication

DNS and Name Resolution

Query DNS directly and recognize when a hostname problem is different from a reachability problem.

35 min INTERMEDIATE LINUX
Before this lab
Lab LAB-NET-02 - Ping and Reachability
What success looks like
  • Query DNS directly and recognize when a hostname problem is different from a reachability problem.
  • Repeat the workflow without copy-paste or step-by-step prompting.
Safety notes
  • Run network changes in a lab or VM first so you do not break your active connection unexpectedly.

Part A: The Field Guide

A hostname problem is not automatically a connectivity problem.

This lab keeps DNS focused on a few usable ideas:

  • query a name directly
  • compare raw IP reachability with hostname resolution
  • remember that local overrides can change the answer

Practical Distinction

If an IP works but the hostname does not, DNS or local name-resolution state becomes a much better suspect than the whole network.

Part B: The Drill Deck

Terminal required: use direct queries and simple comparisons.

G
Guided Step by step - type exactly this and compare the result
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Exercise G1: Run a direct DNS query

  1. Run dig google.com
  2. Find the answer section
  3. Identify the returned address information

Exercise G2: Use the short form

  1. Run dig +short google.com
  2. Notice how much simpler the output is
  3. Explain when the short form is more practical

Exercise G3: Compare IP and hostname behavior

  1. Run ping -c 1 8.8.8.8
  2. Run ping -c 1 google.com
  3. Explain what extra dependency the second command has
S
Solo Task described, hints available - figure it out
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Exercise S1: Look up a different record type

  1. Run dig MX google.com
  2. Notice that the answer is not an IP address in the same format as an A record
  3. Explain what kind of question you just asked DNS

Exercise S2: Hosts-file reasoning

Without editing anything yet, explain one useful reason to override a hostname locally and one reason that override can become confusing later.

M
Mission Real scenario - no hints, combine multiple skills
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Mission M1: Write a DNS troubleshooting mini-flow

Write out a short sequence for the case where a hostname is failing:

  1. test raw IP reachability
  2. query DNS directly
  3. consider local overrides such as the hosts file

If that order feels natural, the DNS lesson is landing well.

What to do next

Best next step Learning

Return to the related lesson if you want the concept explained more deeply.

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Troubleshooting

Use problem-first help when this lab maps to a real issue.

Open now Reference

Look up commands, topics, and tasks while you practice.

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