Quiz — Troubleshooting & Network Security
Module quiz on NAT, firewalls, and network troubleshooting
Module 5 Knowledge Check — NAT, firewalls, layered triage
You learned PAT/NAPT (many private hosts, one public IP), inbound vs outbound and port forwarding as an explicit hole, default-deny firewalls (stateful vs simple ACL, host vs network), and an OSI-aligned checklist that does not treat ping as omniscience. Ten APPLY scenarios. Scope is still your machine and a network you own unless a question says otherwise. Next: Switches, Hubs & MAC Addresses — how frames move on the LAN you have been routing through.
APPLY: A home LAN has fifteen devices on 192.168.1.0/24 and one ISP IPv4 address. Outbound HTTPS works from every laptop. What is doing the sharing, and what field keeps flows distinct on the WAN?
APPLY: Unsolicited inbound TCP to a home public IP:443 has no port-forward and no IPv6. Outbound browsing still works. Best explanation?
APPLY: A game fails to host. A forum says "turn off Windows Firewall and ufw." What is the classic wrong, and what is the right shape?
APPLY: Which pair correctly contrasts firewall types? (Select 2)
APPLY: ping 127.0.0.1 works, ip link shows wlan0 DOWN, and curl to any site fails. Which rung should you fix first?
APPLY: ping to 8.8.8.8 fails from a hardened laptop, but curl -I https://example.com succeeds (you are allowed to use that site). Best conclusion?
APPLY: True or False: After ip addr shows a valid LAN CIDR, the next isolation questions are "is there a default via?" then "does the name resolve?" then "does curl -I complete?" — not "nmap the /24."
APPLY: ss -tuln on your VM shows 0.0.0.0:22 and 127.0.0.1:8080. You will take the laptop to a café. Which bind is the larger LAN exposure if the host firewall is weak?
APPLY: getent hosts intranet.example returns an IP, but curl -I https://intranet.example fails with a certificate hostname mismatch. Which layer is the finding?
APPLY: You finished Troubleshooting & Network Security. What does the next lesson actually open, and what is still out of scope?