Practice Use drills for recall and labs for real operating judgment.

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 Curriculum-reviewed
Prerequisites
Lab LAB-NET-02 - Ping and Reachability
Success criteria
  • Use a DNS query tool directly.
  • Explain the difference between DNS answers and basic connectivity.
Safety notes
  • Be careful with hosts-file edits on real systems; local overrides can create confusing behavior later.

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.