Operation of Running Systems

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

Which TWO commands can be used to view logs for a specific systemd unit (e.g., sshd.service)?

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?

Which THREE of the following are valid options for the `lsblk` command to display more detailed information about block devices? (Select THREE.)

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?

A service is using a port that conflicts with another application. Which command can be used to identify which process is listening on a specific TCP port?

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

During boot, the system drops into a shell with message 'ERROR: No suitable file system found'. Filesystem corruption is suspected. Which sequence of actions should the admin take to attempt recovery?

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

A junior admin runs 'systemctl restart httpd' but the httpd service fails to start. Which command should the admin use first to diagnose the problem?

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.

Refer to the exhibit. How many days of logs are retained before deletion?

You are a systems administrator for a company that runs a high-traffic web application on a Linux server with 32 GB of RAM and 8 CPU cores. The application uses Apache with mod_php and MySQL. Recently, the server has been experiencing intermittent slowdowns, especially during peak hours. Monitoring tools show that the CPU usage spikes to 100% for several minutes and then returns to normal. The 'top' command shows that the 'mysqld' process is often the top CPU consumer during these spikes. You notice that the MySQL slow query log contains many entries with long execution times. The database is heavily used by the web application for read-heavy workloads. After analyzing the situation, you suspect that the issue is related to MySQL configuration. Which of the following actions is most likely to resolve the performance issue?

Match each file system type to its typical use case.

To display the current runlevel on a system using SysV init, which command should be used?

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?

An administrator notices that the system clock is drifting significantly. To synchronize time using NTP, which command should be used to immediately sync with a server?

A Linux administrator is troubleshooting a service that is running as the 'nobody' user but keeps failing because it cannot write to its log file. The log file is located at /var/log/app.log. Which TWO of the following methods will allow the service to write to the log file while maintaining security best practices?

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 production web server is experiencing intermittent high load. The administrator suspects that a specific Apache module is causing memory leaks. Which approach is most effective for isolating the issue without restarting the server?

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

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?

A system administrator needs to monitor real-time network traffic on a specific interface (eth0). Which TWO tools can be used for packet-level analysis?

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

Which THREE methods can be used to rescue a Linux system that fails to boot past GRUB? (Choose three.)

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?

Which THREE steps are necessary to permanently disable a systemd service from starting at boot?

Which THREE commands can show the current system time and date?

A Linux server experiences a kernel panic during boot. The administrator needs to capture the kernel panic message for debugging. Which of the following methods would allow capturing the panic message?

A system administrator notices that logrotate did not rotate the /var/log/messages file on a CentOS 7 server despite having a configuration at /etc/logrotate.d/syslog. The admin runs 'logrotate -d /etc/logrotate.conf' and sees that the syslog file is excluded due to 'olddir' option, but the olddir does not exist. Additionally, the logrotate status file (/var/lib/logrotate/logrotate.status) shows that /var/log/messages was last rotated 30 days ago. The logrotate cron job is scheduled daily. What is the most likely reason the rotation fails?

To permanently mount an ext4 filesystem at /data with noatime option, which entry should be added to /etc/fstab?

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

A cron job runs a script that outputs to stdout. The administrator wants to capture both stdout and stderr to a file named job.log, while also seeing output on the terminal. Which command achieves this?

An administrator wants to schedule a one-time task to run at 2:30 PM next Friday. Which command should be used?

Refer to the exhibit. Based on the exhibit, which service is configured to accept connections only from the local machine?

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

An engineer wants to list all processes currently running under user 'appuser'. Which command is appropriate?

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?

Which TWO of the following commands can be used to display the current kernel ring buffer messages? (Select TWO.)

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?

Which TWO of the following are valid methods to check the status of a systemd service named 'httpd'? (Select TWO.)

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?

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 has a RAID 5 array that is degraded. One of the three disks failed and was replaced. The administrator runs 'cat /proc/mdstat' and sees that the array is still degraded. Which command should be used to add the new disk (/dev/sdc1) to the array?

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?

Match each Linux networking command to its primary function.

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

A system administrator needs to find all files that are larger than 100MB in the /var directory. Which command accomplishes this?

A systems administrator receives reports that a web server running Nginx is intermittently unresponsive. The server has 8 GB of RAM and 4 CPU cores. The administrator runs 'free -m' and sees that available memory is low, and 'top' shows that several nginx worker processes are using a high percentage of CPU. Which of the following is the most likely cause of the issue?

Based on the exhibit, what happens if the service 'myapp' crashes?

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?

You are a systems administrator for a company that runs a web application on a Linux server with 16 GB of RAM and 4 CPU cores. The application uses Apache with mod_php and PostgreSQL. Recently, the server has been experiencing high load average (above 10) and the website is responding slowly. The 'top' command shows that many 'httpd' processes are in 'D' (uninterruptible sleep) state. The 'iostat -x 1' output shows high disk utilization (over 90%) and high average wait times (await > 200 ms) on the disk where PostgreSQL data is stored. The database is write-heavy, and you suspect that disk I/O is the bottleneck. Which of the following actions is most likely to improve the performance?

A system administrator needs to ensure that a specific service, 'myapp', starts automatically after a system crash and also restarts if it fails. Which systemd unit directive should be used to achieve this behavior?

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 server with multiple network interfaces has intermittent connectivity issues. The administrator suspects routing table misconfiguration. Which command would show the current routing table?

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

A Linux server experiences intermittent high load averages but low CPU utilization. The administrator suspects an I/O bottleneck. Which command best identifies the specific device causing the bottleneck?

Which TWO commands can be used to check and repair an ext4 file system that is mounted as /data? (Choose two.)

A developer reports that a web application is running out of file descriptors. Which sysctl parameter should be reviewed and potentially increased?

A Linux system reports 'Out of memory' errors frequently. The administrator checks memory usage with 'free -m' and notices that most memory is used by file cache. Which command can the administrator run to immediately free up the cache without affecting running processes?

An administrator needs to schedule a cron job that runs a script every day at 3:00 AM, but the system is in a different time zone (UTC) than the administrator's local time (EST). The administrator wants the job to run at 3:00 AM local time regardless of system time zone changes. What is the best approach?

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?

Which THREE factors can cause a system to fail to boot after changing kernel boot parameters in GRUB?

Refer to the exhibit. What is the most likely issue with the Apache web server?

Refer to the exhibit. Which filesystem is close to full capacity?

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?

Based on the exhibit, what is the most likely cause of the nginx failure and the appropriate first step to resolve it?