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LFCS Mock Exam 2

This is a second mock exam for LFCS covering all major topics: Operations, Networking, Storage, Essential Commands, and Users & Groups.

Instructions

  • Complete the exercises without looking at the answers.
  • Answers are provided at the end of the document.

Part 1: Operations & Deployment

  1. Temporarily disable a kernel module usb_storage and verify it is no longer in use.
  2. List all currently loaded kernel modules and identify one used by the system audio.
  3. Schedule a one-time job to run /usr/local/bin/update_logs.sh in 15 minutes.
  4. Check system boot messages for any hardware errors.

Part 2: Networking

  1. Configure interface eth1 to use DHCP.
  2. Verify DNS resolution for example.com.
  3. Open port 8080 for TCP connections and make the change persistent.
  4. Create a bonding device bond0 using interfaces eth0 and eth1.

Part 3: Storage

  1. Create a new 5 GB logical volume lv_backup in volume group vg01.
  2. Format it with XFS and mount it at /mnt/backup.
  3. Add a new swap partition on /dev/sdc1 and activate it.
  4. Mount a CIFS share //server/share on /mnt/cifs with credentials stored securely.

Part 4: Essential Commands

  1. Monitor memory usage in real-time and identify the process using the most memory.
  2. Find all .log files larger than 50 MB in /var/log.
  3. Generate a private key and CSR for a certificate signing request.
  4. Clone a Git repository, create a new branch feature1, and push it to the remote.

Part 5: Users & Groups

  1. Create a system user service1 without login permissions.
  2. Set a hard limit of 10 processes for user developer1.
  3. Set ACL so that group developers has read/write access to /opt/project/config.yml.
  4. Configure the system to authenticate users against an LDAP server and verify an LDAP user.

Answers (Do not read until done!)

Part 1: Operations & Deployment

  1. sudo modprobe -r usb_storage lsmod | grep usb_storage (should show nothing)
  2. lsmod | grep snd (example: snd_hda_intel)
  3. echo "/usr/local/bin/update_logs.sh" | at now + 15 minutes
  4. dmesg | less or journalctl -b

Part 2: Networking

  1. sudo nmcli con mod eth1 ipv4.method auto sudo nmcli con up eth1
  2. dig example.com or nslookup example.com
  3. sudo firewall-cmd --permanent --add-port=8080/tcp sudo firewall-cmd --reload
  4. sudo nmcli con add type bond con-name bond0 ifname eth0,eth1 mode active-backup

Part 3: Storage

  1. sudo lvcreate -L 5G -n lv_backup vg01
  2. sudo mkfs.xfs /dev/vg01/lv_backup sudo mkdir -p /mnt/backup sudo mount /dev/vg01/lv_backup /mnt/backup
  3. sudo mkswap /dev/sdc1 sudo swapon /dev/sdc1
  4. sudo mount -t cifs -o credentials=/root/.cifs_credentials //server/share /mnt/cifs

Part 4: Essential Commands

  1. htop or top and sort by memory usage
  2. find /var/log -type f -name "*.log" -size +50M
  3. openssl req -new -newkey rsa:2048 -nodes -keyout server.key -out server.csr
  4. git clone <url> cd <repo> git checkout -b feature1 git push -u origin feature1

Part 5: Users & Groups

  1. sudo useradd -r -s /usr/sbin/nologin service1
  2. Add to /etc/security/limits.conf: developer1 hard nproc 10
  3. setfacl -m g:developers:rw /opt/project/config.yml
  4. Install and configure LDAP client (libnss-ldap, libpam-ldap) Verify: getent passwd ldapuser
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