EX200 Operate running systems Practice Test 2 — 15 Questions

Question 1

After restoring files from backup, an SELinux context of a directory is not correct. Which command will restore the file contexts to the system defaults?

Accepted Answer

restorecon -R /directory. The `restorecon -R /directory` command reads the default SELinux contexts from the policy (stored in the file_contexts database) and applies them recursively to the specified directory. This is the standard method to reset file contexts to system defaults after a restore or misconfiguration.

Answer

chcon -R default_t /directory

Answer

semanage fcontext -R /directory

Answer

setfiles -v /directory

Question 2

Which two commands can be used to view systemd journal entries for the sshd service?

Accepted Answer

journalctl -u sshd. `journalctl -u sshd` filters the systemd journal to show only log entries associated with the `sshd.service` unit. This is the standard way to view service-specific logs in a systemd-based system, as it uses the unit name directly. Option C is also correct because `_SYSTEMD_UNIT=sshd.service` is a systemd journal field that matches the exact unit name, providing an equivalent filter to `-u sshd`.

Answer

systemctl status sshd

Answer

grep sshd /var/log/messages

Answer

tail -f /var/log/secure

Question 3

Which three network configuration methods are valid in RHEL 8/9?

Accepted Answer

/etc/sysconfig/network-scripts/ifcfg-* files. In RHEL 8/9, the traditional `/etc/sysconfig/network-scripts/ifcfg-*` files are still supported for backward compatibility, though NetworkManager is the default service. These files define interface configurations using variables like `DEVICE`, `BOOTPROTO`, and `ONBOOT`, and are read by the `ifup`/`ifdown` scripts or NetworkManager when configured to use them. This method remains valid for static or DHCP-based network setup without requiring a GUI.

Answer

system-config-network

Answer

ifconfig

Question 4

Which three commands can be used to display overall memory usage information?

Accepted Answer

free. The 'free' command displays the total, used, and available physical and swap memory on the system. It reads /proc/meminfo and presents a concise summary of memory usage, making it a primary tool for checking overall memory consumption.

Answer

uptime

Answer

ps aux

Question 5

Refer to the exhibit. Which command would free up the most space immediately?

Accepted Answer

journalctl --vacuum-size=500M. The correct answer is C because journalctl --vacuum-size=500M directly reduces the systemd journal size, which is typically the largest consumer of disk space on a RHEL system. In contrast, yum clean all clears only package caches (relatively small), logrotate -f rotates logs but does not delete old ones by default, and rm -rf /var/log/* is destructive and not recommended even though it could free space; the exhibit (if shown) would confirm that the journal dominates disk usage, making C the most appropriate and immediate space-freeing command.

Answer

yum clean all

Answer

rm -rf /var/log/*

Answer

logrotate -f /etc/logrotate.conf

Question 6

Refer to the exhibit. The web server fails to start. What is the most likely cause?

Accepted Answer

SELinux context is correct, but httpd is not enabled.. The exhibit shows that the web server fails to start, but the SELinux context is correctly set to `httpd_sys_content_t` for the web content files. The most likely cause is that the `httpd` service is not enabled, meaning it is not set to start automatically at boot or has not been started manually. This is a common operational oversight where the service is installed and configured but not activated via `systemctl enable httpd` or `systemctl start httpd`.

Answer

SELinux context is wrong and should be httpd_sys_content_t.

Answer

The index.html file is missing.

Answer

httpd is masked.

Question 7

A system administrator receives reports that a web server service (httpd) fails to start after a reboot. The administrator checks the service status and sees it is disabled. Which of the following is the most appropriate command to ensure the service starts automatically on future reboots?

Accepted Answer

systemctl enable httpd. The `systemctl enable httpd` command creates the necessary symlinks in the systemd unit configuration directory (typically `/etc/systemd/system/multi-user.target.wants/`) to ensure the httpd service starts automatically at boot. Since the service is disabled after reboot, enabling it is the correct action to set it to start on future reboots.

Answer

systemctl start httpd

Answer

systemctl restart httpd

Answer

systemctl daemon-reload

Question 8

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

Accepted Answer

Another process is already listening on port 22.. The failure message indicates that the SSH daemon cannot start because port 22 is already in use. Option B is correct because the error 'Address already in use' or 'bind to port 22 failed' directly points to another process occupying the port, preventing sshd from binding. This is a common port conflict scenario, not a configuration syntax or service enablement issue.

Answer

The SSH daemon is already running on another port.

Answer

The sshd configuration file has a syntax error.

Answer

The service is not enabled.

Question 9

Which TWO commands can be used to view recent systemd journal logs for the current boot?

Accepted Answer

journalctl -b. `journalctl -b` displays logs from the current boot, which is the default behavior when no boot ID is specified. This command directly queries the systemd journal for messages generated during the current system session.

Answer

journalctl -p err

Answer

journalctl --list-boots

Answer

journalctl --since today

Question 10

A server running Red Hat Enterprise Linux 9 experiences high system load (load average 15 on a 4-core system) and slow response times. The administrator runs 'top' and sees that the 'kworker' processes are consuming significant CPU time. Further investigation reveals that the system is performing heavy I/O operations on the root filesystem, which is formatted as XFS. The administrator wants to reduce the impact of filesystem maintenance tasks on system performance. Which of the following actions should the administrator take?

Accepted Answer

Set the dirty ratio sysctl parameters (vm.dirty_ratio and vm.dirty_background_ratio) to lower values.. The high system load is caused by heavy I/O operations, and the kworker processes indicate kernel threads handling writeback. Lowering vm.dirty_ratio and vm.dirty_background_ratio reduces the amount of dirty pages that accumulate before writeback begins, which prevents large bursts of I/O and smooths out disk writes, thereby reducing the impact on system performance.

Answer

Increase the value of the 'nr_requests' queue parameter for the underlying block device.

Answer

Mount the filesystem with the 'noatime' option to reduce metadata updates.

Answer

Schedule filesystem checks (fsck) to run during off-peak hours using a cron job.

Question 11

A system administrator needs to ensure a service called 'myapp' starts automatically at boot and also start it immediately without affecting the current boot configuration. Which TWO commands should be used?

Accepted Answer

systemctl start myapp. The 'systemctl enable myapp' command creates the necessary symlinks so that the service starts automatically at boot, while 'systemctl start myapp' launches the service immediately in the current session without altering the boot configuration. Together, they satisfy both requirements without affecting the existing boot setup.

Answer

systemctl daemon-reload myapp

Answer

systemctl restart myapp

Answer

systemctl activate myapp

Question 12

Refer to the exhibit. What is the most likely cause of the httpd service failure?

Accepted Answer

The Apache configuration has a syntax error.. The most likely cause of the httpd service failing to start is a configuration syntax error (option B). When the Apache configuration contains an invalid directive or syntax mistake, `httpd` will refuse to start and report the error via `apachectl configtest` or `systemctl start httpd`. A missing document root may cause a warning but does not prevent startup; incorrect SELinux context leads to 403 errors but does not stop the service; and a disabled service only affects boot-time startup, not manual starts.

Answer

The httpd service is disabled.

Answer

The /var/www/html directory does not exist.

Answer

SELinux context on /var/www/html/index.html is incorrect.

Question 13

Refer to the exhibit. What is the most likely cause of this failure?

Accepted Answer

Another process is already bound to port 22.. The error message in the exhibit indicates that the sshd service failed to start because port 22 is already in use. This is a classic port conflict, where another process (e.g., another SSH daemon, a web server misconfigured to use port 22, or a leftover process) has bound to the same TCP port. The system log or `ss -tlnp` would show the PID and name of the conflicting process, confirming that port 22 is unavailable for the new sshd instance.

Answer

The sshd service is not enabled.

Answer

SELinux is blocking the service.

Answer

The /etc/ssh/sshd_config file is missing.

Question 14

A junior administrator configured a new network interface (ens224) with a static IP address using a configuration file in /etc/sysconfig/network-scripts/ifcfg-ens224. After restarting the network service, the interface comes up but does not get the IP address. The administrator runs 'ip addr show ens224' and sees no IP address assigned. The interface is listed as DOWN. The administrator then runs 'ifup ens224' manually, which succeeds, and the IP address appears. What is the most likely cause?

Accepted Answer

The ONBOOT directive is set to no in the ifcfg file.. The ONBOOT directive controls whether the interface is automatically brought up at system boot. When set to 'no', the interface configuration file is read but the interface remains DOWN after a network service restart, requiring manual intervention via 'ifup'. The junior administrator's observation that 'ifup ens224' succeeds confirms the configuration is valid, but the interface fails to activate automatically due to ONBOOT=no.

Answer

The network service is not enabled to start at boot.

Answer

The interface name does not match the device file.

Answer

There is a conflict with NetworkManager managing the interface.

Question 15

A system administrator is troubleshooting a custom service called 'database.service' that fails intermittently. The service is a proprietary database that requires large amounts of memory. The administrator runs systemctl status database and sees 'Active: failed (Result: core-dump)' and the journal shows 'Out of memory: Killed process (database) total-vm:...' The server has 8GB RAM and 2 CPU cores. The service unit file does not contain any memory limits. The application is configured to use up to 4GB. The administrator suspects the systemd service is being killed by the OOM killer. Which action should the administrator take to prevent this issue?

Accepted Answer

Set OOMScoreAdjust=-1000 in the service unit file.. Setting OOMScoreAdjust=-1000 makes the systemd service less likely to be targeted by the OOM killer. The OOM killer selects processes based on a badness score; a lower score (down to -1000) reduces the likelihood of being killed. Since the service is already configured to use up to 4GB and the server has 8GB RAM, adjusting the OOM score is the targeted fix without disabling kernel protections or over-allocating resources.

Answer

Set MemoryMax=6G in the service unit file.

Answer

Modify kernel parameters to disable the OOM killer.

Answer

Increase swap space to 16GB.