Operation of Running Systems

An administrator wants to ensure that a service starts automatically after a system crash. Which systemd command should be used?

A developer reports that a custom daemon fails to start after a reboot. The daemon's unit file is located in /etc/systemd/system/custom.service. Which of the following is the most likely cause?

A system administrator needs to ensure that the 'nginx' service starts automatically after a reboot on a system using systemd. The service unit file exists and is currently disabled. Which command should be used?

Which TWO of the following are correct statements about systemd journald configuration?

Which THREE commands can display the current CPU utilization statistics on a Linux system?

An e-commerce company runs a critical application on a Linux server that occasionally becomes unresponsive. The server has 64GB RAM and runs a Java application. The operations team notices that during peak hours, the system becomes very slow and eventually the application crashes with 'OutOfMemoryError'. After restart, it works fine for a while. They suspect a memory leak but also want to ensure the system does not go down during peak hours. The system uses systemd to manage the Java service. The administrator needs to implement a solution that: (1) automatically restarts the service if it becomes unresponsive, (2) limits the memory usage of the service to prevent OOM kills on the system, and (3) provides early warning of high memory usage. Which of the following approaches best meets these requirements?

Based on the journalctl output, what is the most likely cause of the service failure?

Based on the exhibit, what is the most likely cause of the blocked task?

A system administrator notices that a web server process (PID 1234) is consuming excessive CPU. They want to trace its system calls to identify the cause. Which command should be used?

Order the steps to recover a forgotten root password on a Linux system using single-user mode.

Match each file system type to its typical use case.

A system with systemd experiences a service that fails to start due to a 'Failed to start' error with status 203/EXEC. What is the most likely cause?

A junior administrator needs to check the current runlevel and then change the system to runlevel 3 (multi-user, no GUI) on a SysVinit-based system. Which command sequence will accomplish this?

A system administrator wants to view the last 10 lines of the system log file '/var/log/syslog' and continue to watch for new lines as they are appended. Which command should be used?

A Linux server is configured with a custom systemd service unit for a backup script. After editing /etc/systemd/system/backup.service to add an EnvironmentFile directive, the administrator runs 'systemctl start backup' but systemctl status shows the unit still using the old environment. Which command should the administrator run to apply the unit file changes?

A process is stuck in an uninterruptible sleep (D state) and cannot be killed. What is the most likely cause?

A Linux server has a filesystem mounted at /data that is running out of space. The administrator needs to identify which directories under /data are consuming the most disk space and then safely remove old log files. Which two commands should the administrator use? (Choose two.)

A system has a process stuck in uninterruptible sleep (D state). The administrator wants to identify which kernel function it is waiting on. Which tool should be used?

Order the steps to set up a LVM logical volume from a new disk.

A Linux server is configured to boot into a graphical target, but after a recent kernel update, the system hangs at a black screen after the GRUB menu. You can still access a rescue shell via the installation media. Which command should you use to make the system boot into a multi-user text target by default, allowing you to troubleshoot?

A server runs out of inodes. The administrator needs to find which filesystem is exhausted and which directory has the most files. Which command sequence best accomplishes this?

Refer to the exhibit. What is the most likely security issue?

A Linux server's boot process fails after a kernel upgrade. The GRUB2 menu appears, but selecting the newest kernel panics. You need to boot the previous kernel temporarily to recover the system. Which command should you use at the GRUB2 menu to edit the selected entry's boot parameters?

A Linux server is experiencing performance issues. You need to identify which processes are consuming the most CPU and memory in real-time. Which two commands can provide this information interactively? (Choose two.)

Which TWO commands can be used to display real-time process resource usage on a Linux system? (Choose two.)

A user reports that a background process (PID 3456) is consuming 95% of CPU and causing system slowness. The process name is 'crypto-miner'. The administrator needs to immediately stop this process and ensure it does not restart. Which set of commands should the administrator execute?

An administrator is troubleshooting a server that runs a critical application. The server has 16 GB of RAM and 8 CPU cores. The administrator notices that the server becomes very slow during peak hours. Analysis of 'iostat -x 1' shows that the average wait time (await) for the main disk (sda) is consistently above 1000 ms, while the average service time (svctm) is around 5 ms. What is the most likely cause?

To view the system's default runlevel (target) at boot, which command is used on a systemd-based system?

After a kernel update, a service fails to start with 'cannot allocate memory'. The system has 16GB RAM and 8GB swap. Which command should the administrator run first to diagnose potential memory limits?

A server is running out of disk space. Which command will show the disk usage of the root filesystem in a human-readable format?

A Linux server is experiencing performance issues. The administrator suspects that a process is causing excessive disk I/O. Which command should the administrator use to identify the process with the highest disk I/O usage in real-time?

Which command shows the default target for systemd?

A user reports that they cannot log in via SSH, but other users can. The administrator checks /var/log/auth.log and sees 'Failed password for invalid user'. What is the most likely cause?

A system administrator needs to schedule a one-time task that will run at 2:30 AM on July 15. Which command should be used to create this job?

An administrator needs to ensure that a custom service, /usr/local/bin/monitor.sh, starts automatically at boot and is restarted if it crashes. The service should run as user 'monitor' and should not depend on network being online. Which systemd unit file configuration is most appropriate?

A server is experiencing high load, and the administrator suspects a runaway process is consuming excessive CPU. The administrator wants to identify the top CPU-consuming processes and then terminate the most resource-intensive one. Which sequence of commands should the administrator use?

A system running RHEL 8 experiences intermittent crashes. After reboot, 'journalctl -p err -b -1' outputs: 'PID 1234 (myapp) ended due to signal: KILL'. Which diagnostic step should the administrator perform next?

A process (PID 1234) is hung and cannot be killed with SIGTERM. To force termination, which signal should be sent?

A Linux server's root filesystem is filling up quickly. You suspect that a user's process is writing a large log file and that the file has been deleted, but the space is still held. Which command will show the deleted file and the process holding it open?

An administrator wants to view the current memory usage in a human-readable format, showing totals for used and free memory. Which command should be used?

A Linux server has its time zone set to UTC, but the administrator wants the system clock to be synchronized by an internal NTP server at 10.0.0.10. The system uses systemd and chrony is already installed. Which command should the administrator run to configure the NTP server and make it persistent?

A Linux administrator needs to ensure that the 'httpd' service starts automatically at boot and is currently running. The system uses systemd. Which two commands should the administrator use to achieve this? (Choose two.)

A system administrator needs to check the current CPU load and memory usage on a Linux server. Which command should be used to display a dynamic, real-time view of running processes and system resource utilization?

A system administrator notices that a process is consuming 100% CPU and is unresponsive. Which command should be used to immediately stop the process if the PID is 2345?

A systems administrator is troubleshooting a server that runs a database application. The server has 64 GB of RAM and 16 CPU cores. The administrator notices that the system is using a significant amount of swap space even though there is plenty of free memory. The 'free -m' command shows: total memory = 65536, used = 50000, free = 15536, buffers/cache = 10000, swap total = 8192, swap used = 6000. Which of the following is the most likely cause?

A Linux server is experiencing performance degradation. The administrator suspects that a process is consuming excessive CPU. Which two commands can be used to identify the top CPU-consuming processes in real-time? (Choose two.)

Based on the exhibit, which process is using the most physical memory (RES)?

A Linux administrator needs to schedule a backup script to run every day at 2:30 AM. The script is located at /usr/local/bin/backup.sh. Which command should the administrator use to edit the crontab for the root user?

A junior administrator needs to check the current system time and date on a Linux server. Which command will display this information?

A Linux server's root filesystem is running out of space. The administrator needs to identify which directory under /var is consuming the most disk space. Which command should the administrator use?

A system administrator is troubleshooting a production web server running CentOS 7 that became unresponsive. The server is still pingable, but SSH connections timeout. The admin performs an out-of-band console login. The server appears frozen; typing commands shows no output. The admin is able to trigger a Magic SysRq key sequence (Alt+SysRq+f) to kill the hung processes. After that, the server resumes normal operation. However, the admin wants to understand the root cause. Upon checking 'dmesg', they see repeated messages: 'NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s!' followed by stack traces from a kernel thread. Which action should the admin take to prevent recurrence while maintaining system stability?

An administrator is investigating why the 'tomcat' service fails to start on a RHEL 8 server. The output of 'systemctl status tomcat' shows: 'Loaded: loaded (/etc/systemd/system/tomcat.service; enabled; vendor preset: disabled) Active: failed (Result: exit-code) since ... Process: 4567 ExecStart=/opt/tomcat/bin/startup.sh (code=exited, status=1/FAILURE)'. The 'journalctl -u tomcat' shows: 'Error: JAVA_HOME is not defined correctly, cannot execute /usr/lib/jvm/java-11-openjdk/bin/java'. The admin checks /opt/tomcat/bin/startup.sh and sees it references JAVA_HOME. The admin verifies that Java 11 is installed at /usr/lib/jvm/java-11-openjdk. Which action should the admin take to fix the service?