LFCS Certification Preparation

Interpret Linux process hierarchies, states, threads, and key /proc data to identify abnormal execution.

Locate a process's resource usage, open files, and listening sockets with ps, top, pidstat, lsof, and ss.

Control process execution with appropriate signals, nice values, and renice values.

Keep commands running safely across shell sessions using job control, nohup, and terminal multiplexing patterns.

Create a systemd service unit for a long-running application and validate its unit-file syntax.

Configure systemd service ordering, dependencies, enablement, and restart behavior.

Apply systemd drop-ins for environment, identity, resource limits, and selected security constraints.

Diagnose and repair a failed systemd service using unit state, dependencies, exit status, and journal evidence.

Inspect and change a kernel parameter non-persistently with sysctl and verify its runtime effect.

Create a persistent sysctl configuration while resolving precedence and conflicting settings.

Schedule and verify a one-time administrative command with at or systemd-run.

Create a safe recurring job with cron, including explicit environment, logging, and failure handling.

Create and troubleshoot a systemd timer paired with a oneshot service.

Correlate kernel and hardware events using journalctl, dmesg, lsblk, lspci, and device-state evidence.

Enter rescue or emergency mode and use a recovery environment to regain administrative access.

Restore bootability after a faulty kernel parameter, systemd dependency, or /etc/fstab entry prevents normal startup.

Create and modify local users with deliberate UID, home-directory, shell, and supplementary-group settings.

Create and manage local groups and delegated administrative access with validated sudo policy.

Configure password aging, account expiration, locking, and authentication-state checks for a local account.

Implement personal and system-wide environment settings using the appropriate shell and profile files.

Configure and verify per-user resource limits through PAM and limits.d configuration.

Create, inspect, modify, and remove POSIX ACLs while accounting for masks and default ACL inheritance.

Configure an Ubuntu client to resolve LDAP users and groups through SSSD and NSS/PAM integration.

Troubleshoot LDAP identity lookup and login failures using directory queries, SSSD state, caches, permissions, and logs.

Prepare a disposable Ubuntu 24.04 system to boot with SELinux and verify enforcing, permissive, and disabled states.

Assign and restore persistent SELinux file contexts with semanage fcontext and restorecon.

Inspect SELinux process domains and file types to determine whether an access request should be permitted.

Select and change SELinux Booleans while evaluating the permissions they alter.

Diagnose an SELinux denial from audit records without weakening unrelated policy protections.

Build, install, and test a minimal local SELinux policy module for a justified denied operation.

Generate a private key, certificate-signing request, and self-signed test certificate with OpenSSL.

Verify certificate identity, validity, chain, extensions, and private-key correspondence with OpenSSL.

Configure and validate persistent static and DHCP-based IPv4 settings with Netplan.

Configure and validate persistent IPv6 addressing, gateways, and neighbor discovery behavior with Netplan.

Configure a persistent hostname and predict how /etc/hosts affects local name resolution.

Configure and troubleshoot DNS resolution through Netplan and systemd-resolved.

Synchronize system time with Chrony and diagnose an unsynchronized or incorrect clock.

Inspect interfaces, addresses, neighbors, sockets, and routing decisions with iproute2 and ss.

Localize a connectivity failure across link, addressing, routing, transport, and DNS layers.

Capture and interpret packets with tcpdump to validate a networking diagnosis.

Configure OpenSSH client identities, host aliases, and host-key verification for repeatable administration.

Configure OpenSSH server authentication, access restrictions, forwarding controls, and validated reloads.

Diagnose SSH connection failures by separating name resolution, routing, filtering, negotiation, authentication, and session issues.

Create and persist IPv4 and IPv6 static routes with Netplan and verify route selection.

Enable packet forwarding and configure an Ubuntu VM to route traffic between lab networks.

Build and persist a least-privilege filtering policy with iptables and ip6tables on Ubuntu's selected backend.

Configure and verify destination NAT or local port redirection with iptables.

Configure and verify source NAT or masquerading with iptables, counters, and packet captures.

Create a persistent Linux bridge with Netplan and attach interfaces or virtual workloads to it.

Create a persistent bonded interface with Netplan and select a bonding mode appropriate to the lab topology.

Diagnose bridge and bond failures using link state, membership, forwarding, and bond-status evidence.

Configure Nginx as an HTTP reverse proxy while preserving required client and protocol headers.

Configure Nginx to load-balance requests across multiple upstream services.

Configure HAProxy frontends and backends for an HTTP or TCP service and validate the traffic path.

Configure HAProxy health checks and demonstrate backend failure detection and recovery.

Configure TLS termination on a reverse proxy or load balancer and validate the certificate and upstream request flow.

Interpret the Linux virtual filesystem mount hierarchy, mount propagation information, and common pseudo-filesystems with findmnt and /proc.

Create and verify GPT partitions while accounting for device naming and alignment.

Create, label, and inspect ext4 and XFS filesystems and identify their differing maintenance constraints.

Configure persistent filesystem mounts by UUID with appropriate mount options and ordering semantics.

Diagnose a failed or incorrect mount using fstab validation, systemd mount units, logs, and filesystem metadata.

Check and repair an unmounted filesystem with the filesystem-appropriate recovery tool and a safe rollback plan.

Create, prioritize, persist, resize, and remove swap files or partitions safely.

Resolve disk-space discrepancies caused by large paths, exhausted inodes, hidden mount data, reserved blocks, or deleted open files.

Create physical volumes, a volume group, and a deliberately sized logical volume.

Create a filesystem on a logical volume and mount it persistently by stable identifier.

Extend a logical volume and its ext4 or XFS filesystem safely while preserving data.

Create and use an LVM snapshot for a consistent point-in-time recovery exercise.

Move allocated extents away from a physical volume and remove it from a volume group safely.

Deactivate and remove logical volumes, volume groups, and physical volumes in dependency order.

Diagnose LVM discovery, activation, metadata, and missing-device problems with LVM reporting tools and logs.

Identify a storage bottleneck using capacity, latency, throughput, utilization, and per-process I/O evidence.

Configure an NFS export and mount it persistently from an Ubuntu client with suitable access options.

Diagnose NFS access, identity-mapping, version-negotiation, firewall, and stale-handle failures.

Configure direct and indirect autofs maps and verify on-demand mounting and expiration.

Publish a block device from an iSCSI target in an isolated lab network.

Discover, log in to, format, and persistently use an iSCSI LUN from an initiator.

Verify nested-virtualization support inside VMware and configure a libvirt host, storage pool, and virtual network.

Create an Ubuntu virtual machine with virt-install using deliberate CPU, memory, storage, and networking settings.

Manage libvirt virtual-machine lifecycle, autostart, console access, snapshots, and state inspection with virsh.

Install Docker Engine from a validated repository and configure and verify the daemon on Ubuntu 24.04.

Pull, inspect, tag, save, load, and remove container images while distinguishing images from containers.

Write and build a minimal Dockerfile that uses deterministic inputs, efficient layers, and a non-root runtime user.

Run and manage a container with explicit environment, published ports, restart policy, and lifecycle controls.

Select and configure a bind mount or named volume for persistent container data.

Create a user-defined Docker network and verify name-based communication between containers.

Apply and inspect container CPU, memory, user, and Linux-capability constraints.

Diagnose a failing or slow containerized service using Docker state, logs, events, stats, exec, and host networking and storage evidence.