A+ Lab 1 — No Internet: IP vs Route vs DNS
You are no longer just learning terms. This lab is about thinking like a technician: isolate the problem, prove what layer failed, fix it cleanly, and verify the result.
User reports: “My VM has no internet. Websites won’t load.”
Priority: Medium • Scope: Single system • Goal: identify whether the issue is IP assignment, routing, or DNS.
⏱ 20–30 minutes • 📊 Beginner / early A+ • Goal: break → diagnose → fix → verify.
What a Real Tech Should Ask First
- Did it ever work before?
- Is this only this VM, or all devices?
- Can the system reach an IP but not a domain?
- Did anything change in the VM networking settings?
Print mode auto-shows all steps and hides the hero image + progress UI.
What You Need
- UTM installed (Mac)
- Linux VM already installed
- CPU: 2 cores
- RAM: 4–8 GB
- Disk: 30–40 GB
- Network: Enabled and set to a normal/shared mode
Do not assume “no internet” automatically means DNS. First prove whether the VM has an IP, then whether it has a route, then whether name resolution works.
Real-World Translation
“No Internet” is one of the most common support tickets. This same logic applies to laptops, Wi-Fi, VPN users, office desktops, and cloud VMs.
Your job is not to guess. Your job is to isolate the layer: IP/DHCP → routing → DNS.
Break / Diagnose / Fix
Simulate a ticket by creating a networking problem safely.
Option A — Disable networking
- Shut down the VM.
- In UTM, select the VM → Edit.
- Go to Network and disable it or remove the active interface.
- Start the VM again.
Confirm the symptom
ping -c 2 google.com
Expected result: request fails. The VM should behave like it has lost connectivity.
Prove whether the issue is IP, route, or DNS.
Run these commands in order
ip a ip route ping -c 2 8.8.8.8 ping -c 2 google.com
What healthy output means
- ip a → your main interface has an IPv4 address
- ip route → there is a default route
- ping 8.8.8.8 → the VM can reach the outside network by IP
- ping google.com → DNS is working too
What broken output means
- No usable IP in ip a → NIC/DHCP/network mode issue
- No default route in ip route → routing/gateway problem
- 8.8.8.8 fails → connectivity/routing issue
- 8.8.8.8 works but google.com fails → DNS problem
Restore normal networking and prove that the ticket is resolved.
Fix
- Shut down the VM.
- UTM → VM → Edit → Network.
- Re-enable the NIC or restore the working/default network mode.
- Start the VM.
Verify with two independent tests
ping -c 2 8.8.8.8 ping -c 2 google.com
Always verify with both an IP test and a DNS test. One successful website load is not enough evidence.
Write the ticket note
Use: Symptom → Checks → Actions → Result
What This Skill Maps To
- Troubleshooting methodology
- Basic networking diagnostics
- Command-line utilities
- Support verification habits
- Ticket documentation discipline
Self-Check Quiz (Unlock Next Lab)
Score ≥ 75% to unlock the next lab link. Your score is saved on this browser.
1) What is the biggest difference between ITF+ and A+ in this context?
2) A VM cannot reach anything, and ip a shows no usable IP. What is the best diagnosis direction?
3) Which command is most associated with viewing local IP configuration on Linux?
4) If ping 8.8.8.8 works but ping google.com fails, what is most likely broken?
Next Lab
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