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Quiz — Linux Servers

Quiz Overview

Assess Module 7 Advanced Linux Servers skills: baseline, nginx reverse proxy, TLS, LVM/fstab, backups, and exposure control.

Attribute Value
Topic Linux servers
Questions 25
Passing score 70% (18 correct)
Estimated time 30–40 minutes

How to use this quiz

Attempt without peeking. Use Reveal answer only after you choose.

Learning Objectives

  • Choose correct bind/exposure patterns for app servers
  • Operate nginx proxy and TLS basics
  • Reason about LVM/fstab and backup/restore proof
  • Avoid common hardening lockouts

Section 1 — Fundamentals

Question 1

On a hardened app server, where should the application process typically listen?

Difficulty: Beginner

Options:

  • A. 127.0.0.1 on a private port behind nginx
  • B. 0.0.0.0:8080 publicly
  • C. Only on IPv6 link-local
  • D. UDP 53
Reveal answer

Correct answer: A

Localhost bind keeps the app off the public exposure path; nginx owns 80/443.

Related concepts

  • Bind address
  • Reverse proxy

Question 2

Which command best lists TCP listening sockets with processes?

Difficulty: Beginner

Options:

  • A. ping -a
  • B. chmod 777
  • C. sudo ss -tulpn
  • D. tar -tzf
Reveal answer

Correct answer: C

ss replaces netstat for socket inspection.

Related concepts

  • ss

Question 3

What does nginx -t do?

Difficulty: Beginner

Options:

  • A. Terminates TLS
  • B. Truncates access logs
  • C. Opens port 443
  • D. Tests configuration syntax before reload
Reveal answer

Correct answer: D

Always test before reload.

Related concepts

  • nginx

Question 4

A curl to nginx /api returns 502 while curl to 127.0.0.1:18080 fails. Likely?

Difficulty: Intermediate

Options:

  • A. DNS NXDOMAIN only
  • B. Upstream app is down or not listening
  • C. ext4 fragmentation
  • D. Wrong timezone wallpaper
Reveal answer

Correct answer: B

502 usually means upstream problem.

Related concepts

  • 502
  • Upstream

Question 5

Self-signed certificates in labs primarily lack what?

Difficulty: Beginner

Options:

  • A. Public CA trust in browsers
  • B. Encryption capability
  • C. Private keys
  • D. Ports
Reveal answer

Correct answer: A

Self-signed encrypts but is not publicly trusted.

Related concepts

  • TLS

Question 6

Preferred fstab device identifier?

Difficulty: Intermediate

Options:

  • A. /dev/sdb1 always
  • B. IDE bus number
  • C. UUID=...
  • D. Random major:minor
Reveal answer

Correct answer: C

UUIDs survive device rename.

Related concepts

  • fstab
  • UUID

Question 7

After lvextend, ext4 still shows old size until you?

Difficulty: Intermediate

Options:

  • A. Reboot BIOS
  • B. Delete fstab
  • C. Disable nginx
  • D. Run resize2fs (online grow)
Reveal answer

Correct answer: D

Grow the filesystem after the LV.

Related concepts

  • LVM
  • resize2fs

Question 8

What proves a backup is useful?

Difficulty: Beginner

Options:

  • A. File exists on disk
  • B. Checksum verify plus successful restore drill
  • C. Cron ran once
  • D. Screenshot of ls
Reveal answer

Correct answer: B

Untested backups fail incidents.

Related concepts

  • Backup
  • Restore

Question 9

UFW enable without allowing SSH often causes?

Difficulty: Advanced

Options:

  • A. Admin lockout from remote SSH
  • B. Faster TLS
  • C. Automatic LVM extend
  • D. Chrony sync
Reveal answer

Correct answer: A

Allow OpenSSH first; keep console.

Related concepts

  • UFW
  • Lockout

Question 10

chrony/time sync matters for TLS because?

Difficulty: Intermediate

Options:

  • A. Certificates are timezone files
  • B. nginx ignores time
  • C. Validity windows depend on correct clock
  • D. SSH disables NTP
Reveal answer

Correct answer: C

Skew breaks cert validation.

Related concepts

  • NTP
  • TLS

Section 2 — Practical Knowledge

Question 11

sites-enabled on Debian/Ubuntu usually contains?

Difficulty: Beginner

Options:

  • A. Binary modules only
  • B. Private keys only
  • C. LVM metadata
  • D. Symlinks to sites-available configs
Reveal answer

Correct answer: D

Enable via symlink pattern.

Related concepts

  • nginx

Question 12

Automatic-Reboot true on a single stateful VM is risky because?

Difficulty: Intermediate

Options:

  • A. It upgrades DNS
  • B. Unexpected downtime without drain/window
  • C. It disables SSH keys
  • D. It formats /boot nightly
Reveal answer

Correct answer: B

Need change windows on singleton VMs.

Related concepts

  • Unattended upgrades

Question 13

PV → VG → LV describes?

Difficulty: Beginner

Options:

  • A. LVM layering
  • B. nginx stages
  • C. TLS handshake
  • D. systemd targets only
Reveal answer

Correct answer: A

Physical → group → logical.

Related concepts

  • LVM

Question 14

Which ports are typical public edge for this design?

Difficulty: Beginner

Options:

  • A. 18080, 5432, 6379
  • B. Only 8080
  • C. 22, 80, 443
  • D. 137–139
Reveal answer

Correct answer: C

SSH + HTTP/HTTPS; app private.

Related concepts

  • Exposure matrix

Question 15

openssl x509 -enddate helps you?

Difficulty: Beginner

Options:

  • A. Extend LVM
  • B. Ban SSH IPs
  • C. Compile nginx
  • D. See certificate expiry
Reveal answer

Correct answer: D

Monitor notAfter.

Related concepts

  • OpenSSL

Question 16

rsync --delete danger?

Difficulty: Intermediate

Options:

  • A. It encrypts twice
  • B. Can wipe backup target to mirror source deletions
  • C. Disables checksums forever
  • D. Requires IPv6
Reveal answer

Correct answer: B

Dry-run first.

Related concepts

  • rsync

Question 17

proxy_pass to http://127.0.0.1:18080/ from location /api/ is for?

Difficulty: Intermediate

Options:

  • A. Reverse proxy to local upstream
  • B. Static files only
  • C. Firewall bypass on WAN
  • D. LVM snapshots
Reveal answer

Correct answer: A

Core reverse proxy pattern.

Related concepts

  • nginx
  • proxy_pass

Section 3 — Scenarios & Operations

Question 18

fail2ban primarily mitigates?

Difficulty: Beginner

Options:

  • A. Disk full
  • B. Certificate expiry
  • C. Brute-force auth attempts (e.g. sshd)
  • D. Slow DNS
Reveal answer

Correct answer: C

Ban repeat offenders.

Related concepts

  • fail2ban

Question 19

Loop-backed LVM labs are used to?

Difficulty: Advanced

Options:

  • A. Replace cloud disks always
  • B. Speed up TLS
  • C. Disable fstab
  • D. Practise safely without risking system disks
Reveal answer

Correct answer: D

Safe pedagogy.

Related concepts

  • LVM lab

Question 20

3-2-1 backup rule emphasises?

Difficulty: Intermediate

Options:

  • A. One disk only
  • B. Multiple copies/media and off-site copy
  • C. RAID equals backup
  • D. Snapshots only in RAM
Reveal answer

Correct answer: B

Industry practice.

Related concepts

  • Backup

Question 21

server_tokens off reduces?

Difficulty: Beginner

Options:

  • A. Version disclosure in nginx headers
  • B. CPU
  • C. Disk inodes
  • D. SSH banner colour
Reveal answer

Correct answer: A

Slight hardening.

Related concepts

  • nginx security

Question 22

When certbot HTTP-01 fails on pure localhost?

Difficulty: Intermediate

Options:

  • A. openssl is broken
  • B. UFW must disable lo
  • C. No public DNS/HTTP challenge path — use self-signed/internal CA for lab
  • D. LVM full
Reveal answer

Correct answer: C

ACME needs reachability.

Related concepts

  • Let's Encrypt

Question 23

systemd-analyze blame helps baseline by?

Difficulty: Intermediate

Options:

  • A. Rotating nginx logs
  • B. Issuing certificates
  • C. Creating VGs
  • D. Listing slow boot units
Reveal answer

Correct answer: D

Boot cost visibility.

Related concepts

  • systemd-analyze

Question 24

Connection refused on :443 but nginx active — check?

Difficulty: Advanced

Options:

  • A. Only dpkg holds
  • B. Listen directives / firewall / wrong IP
  • C. tar format
  • D. Python GIL
Reveal answer

Correct answer: B

Socket and path triage.

Related concepts

  • Troubleshooting

Question 25

Least privilege sudo for deploy user means?

Difficulty: Beginner

Options:

  • A. Allow-list specific commands (e.g. systemctl reload nginx)
  • B. NOPASSWD ALL
  • C. Share root password
  • D. Disable sudo logging
Reveal answer

Correct answer: A

Command allow-lists.

Related concepts

  • sudoers

Score Summary

Score Band Meaning
23–25 Excellent Ready for the app-server lab and interviews
18–22 Good Pass — revise weak Module 7 tutorials
12–17 Needs improvement Revisit nginx/TLS/LVM labs
≤11 Restart Module 7 Work tutorials 21–25 in order

Total questions: 25 · Passing score: 18 (70%)

Interview Connection

Expect bind-address, nginx 502, certificate expiry, fstab UUID, and backup-restore questions. Use your Module 7 lab story.

References

  1. nginx documentation
  2. Ubuntu Server docs
  3. LVM HOWTO