EX200 Practice Test 17 — 15 Questions

Question 1

An IT department runs a web server that stores user uploads on an ext4 filesystem on /dev/sdb1 mounted at /uploads. Recently, the partition has run out of space. The administrator checks with df -h and sees 100% usage. However, du -sh /uploads shows only 2GB used. The administrator suspects deleted files still held open by processes. Which command should be used to identify and resolve the issue?

Accepted Answer

lsof +L1 /uploads to find deleted open files, then kill processes. Option D is correct because the discrepancy between `df -h` showing 100% usage and `du -sh /uploads` showing only 2GB indicates that deleted files are still held open by running processes. The `lsof +L1 /uploads` command lists files with a link count of zero (deleted but still open), and killing the associated processes releases the disk space. This is a classic scenario on ext4 filesystems where file descriptors prevent space reclamation until the process closes the file.

Answer

rm -rf /uploads/* to clean all files

Answer

fsck /dev/sdb1 to repair filesystem

Answer

resize2fs /dev/sdb1 to shrink filesystem

Question 2

A system administrator is setting up storage for a new application server. The application requires two separate filesystems: one for the database (needs to be at least 10GiB) and one for logs (needs at least 5GiB). The server has a single 20GiB disk /dev/sda. The administrator plans to use LVM and a single volume group 'vg_app'. They create physical volume on /dev/sda, create the volume group, and then create two logical volumes: 'lv_db' of 10GiB and 'lv_logs' of 5GiB. They format lv_db as ext4 and lv_logs as xfs, and mount them at /db and /logs respectively. After rebooting, the system fails to mount /logs. What is the most likely cause?

Accepted Answer

The /logs entry is missing from /etc/fstab.. The most likely cause is that the /logs entry is missing from /etc/fstab. After reboot, the system relies on /etc/fstab to mount filesystems automatically. Since the administrator created and mounted the filesystem manually, but did not add an entry for /logs in /etc/fstab, the mount fails on reboot. The database mount may succeed if it was added, but the logs mount fails due to the missing fstab entry.

Answer

The logical volume 'lv_logs' overlaps with 'lv_db'.

Answer

The physical volume /dev/sda is not recognized by LVM after reboot.

Answer

The volume group 'vg_app' is not automatically activated.

Question 3

You are a system administrator for a small company. The development team has created a shell script named 'deploy.sh' that automates deployment of a web application. The script is located at /home/devops/deploy.sh. The team reports that when they run the script with './deploy.sh' from the /home/devops directory, it fails with a 'Permission denied' error. However, running 'bash deploy.sh' works fine. Additionally, the script's first line is '#!/bin/bash' and the file permissions are '-rw-rw-r--'. The team wants to be able to run the script directly without typing 'bash'. Which of the following actions should you take to resolve the issue?

Accepted Answer

Add the execute permission to the script using 'chmod +x /home/devops/deploy.sh'.. Option C is correct because the 'Permission denied' error when running './deploy.sh' indicates that the script lacks execute permission. The current permissions '-rw-rw-r--' show read/write for owner and group, and read-only for others, but no execute bit. Adding execute permission with 'chmod +x' allows the script to be run directly via its shebang line.

Answer

Change the shebang line to '#!/bin/sh' because bash is not the default shell.

Answer

Move the script to /usr/local/bin so it can be found in the PATH.

Answer

Change the owner of the script to root using 'chown root:root /home/devops/deploy.sh'.

Question 4

Refer to the exhibit. Which command will ensure cron jobs run automatically at system boot?

Accepted Answer

systemctl enable crond. The `systemctl enable crond` command creates the necessary symlinks in the systemd unit configuration to ensure the `crond` service starts automatically at boot. This is the correct method to enable a service for automatic startup in a systemd-based Red Hat Enterprise Linux system.

Answer

systemctl reenable crond

Answer

systemctl start crond

Answer

systemctl unmask crond

Question 5

Refer to the exhibit. An administrator sees that a user from 192.168.1.101 cannot connect to the SSH server. Based on the log, what is the most probable cause?

Accepted Answer

The client's host key type is not supported by the server. Option A is correct. The log clearly states 'no matching host key type found'. This indicates the client offers host key types that the server does not support. Option B is possible but not indicated in the log. Option C is unlikely because the service accepted connections from other IPs. Option D is not shown.

Answer

The server's firewall is blocking the connection

Answer

The SSH service is not running

Answer

The client's IP is blacklisted

Question 6

A systems administrator installs a custom hardware device driver kernel module named 'mydevice' on a RHEL 9 system. The module is built and placed in /lib/modules/$(uname -r)/extra/. The administrator loads it manually with modprobe mydevice and it works. However, after a system reboot, the module is not loaded. The administrator checks that the device is present at boot time. Which step should be taken to ensure the module loads automatically at boot?

Accepted Answer

Run 'echo mydevice > /etc/modules-load.d/mydevice.conf'. Option D is correct because writing the module name to a file in /etc/modules-load.d/ ensures systemd loads the module automatically at boot. The modules-load.d mechanism is the standard RHEL 9 method for specifying kernel modules to be loaded early in the boot process, before the root filesystem is fully available.

Answer

Add the line 'install mydevice /sbin/modprobe --ignore-install mydevice' to /etc/modprobe.d/load.conf

Answer

Rebuild the initramfs with 'dracut --force --add mydevice'

Answer

Add the line 'load mydevice' to /etc/rc.local and ensure rc.local is executable.

Question 7

A cron job runs a script every hour and leaves many log files. The administrator wants to clean up log files older than 7 days in /var/log/myapp/. Which command should be added to a weekly cron job?

Accepted Answer

find /var/log/myapp -type f -mtime +7 -delete. Option D is correct because `-mtime +7` matches files whose modification time is older than 7 days, and `-delete` safely removes them. This is the most efficient and standard approach for cleaning up old log files in a cron job, as it avoids spawning a separate process for each file.

Answer

find /var/log/myapp -type f -atime +7 -delete

Answer

find /var/log/myapp -type f -mtime +7 -exec rm {} \;

Answer

find /var/log/myapp -type f -ctime +7 -delete

Question 8

An administrator needs to add a 2GB swap file to a system that already has swap partitions. Which set of commands will create and activate the swap file correctly?

Accepted Answer

fallocate -l 2G /swapfile; mkswap /swapfile; swapon /swapfile. Option A is correct because `fallocate` pre-allocates a 2GB file efficiently without writing data blocks, then `mkswap` sets up the swap signature, and `swapon` activates it. This is the recommended method for creating swap files on modern Linux systems, as it avoids the overhead of writing zeros with `dd`.

Answer

mkfile 2G /swapfile; mkswap /swapfile; swapon /swapfile

Answer

dd if=/dev/zero of=/swapfile bs=1M count=2048; mkswap /swapfile; swapon /swapfile

Answer

touch /swapfile; truncate -s 2G /swapfile; mkswap /swapfile; swapon /swapfile

Question 9

On a default Red Hat Enterprise Linux 8 installation, which THREE tools or files can be used to configure time synchronization?

Accepted Answer

chronyc. On a default Red Hat Enterprise Linux 8 installation, `chronyd` is the default NTP daemon, and its configuration file is `/etc/chrony.conf`. The `chronyc` command is the command-line interface for interacting with the `chronyd` daemon, allowing you to monitor and adjust time synchronization. `timedatectl` is the systemd-based tool for managing system time and date settings, including enabling NTP synchronization via `chronyd`.

Answer

ntpq

Answer

/etc/ntp.conf

Question 10

Refer to the exhibit. A user 'alice' is unable to write to /data directory. What is the most likely reason?

Accepted Answer

The directory permissions restrict access. The correct answer is A because the exhibit (not shown here) likely displays directory permissions such as 'drwxr-xr-x' or 'drwx------' that do not grant write access to the user 'alice'. In Linux, the write permission (w) on a directory controls whether a user can create, delete, or rename files within it. Since 'alice' lacks write permission on /data, she cannot write to it, regardless of ownership or filesystem space.

Answer

The filesystem is nearly full

Answer

The directory is owned by root and alice is not root

Answer

The directory has ACLs preventing access

Question 11

Which TWO commands can be used to display the current SELinux mode?

Accepted Answer

sestatus. The `sestatus` command displays the current SELinux mode (enforcing, permissive, or disabled) along with other SELinux status information. The `getenforce` command specifically returns only the current SELinux mode as a string (Enforcing, Permissive, or Disabled). Both are standard tools for checking the SELinux operational state.

Answer

checkmodule

Answer

seinfo

Answer

setenforce

Question 12

An administrator needs to create a network bond interface 'bond0' with two slave interfaces 'eth0' and 'eth1' using active-backup mode. Which set of commands is correct?

Accepted Answer

nmcli con add type bond ifname bond0; nmcli con add type ethernet ifname eth0 master bond0 slave-type bond. Option A is correct because it uses `nmcli` to first create a bond interface named 'bond0' with the default active-backup mode, then adds an Ethernet connection for 'eth0' as a slave to 'bond0' using the `master bond0 slave-type bond` parameters. This is the standard NetworkManager approach for bonding in RHEL 8/9, ensuring the bond is managed by NetworkManager and the slave is properly attached.

Answer

Edit /etc/sysconfig/network-scripts/ifcfg-bond0 and ifcfg-eth0 manually

Answer

teamd -d -c '{"device":"bond0","runner":{"name":"activebackup"},"ports":{"eth0":{},"eth1":{}}}'

Answer

nmcli con add type bond ifname bond0; nmcli con add type bond-slave ifname eth0 master bond0

Question 13

A cron job fails to run. Which command should the administrator use to verify the cron daemon is active?

Accepted Answer

systemctl status crond. 'systemctl status crond' checks the status of the cron daemon. Option B is incorrect because the service name is 'crond', not 'cron'. Option C uses 'service' which is legacy. Option D checks for systemd units but not specifically cron.

Answer

systemctl status cron

Answer

systemctl list-units --type=service

Answer

service crond status

Question 14

A web server running Apache (httpd) on RHEL 9 serves content from /var/www/custom. Clients get a 403 error. The SELinux context on files is system_u:object_r:default_t:s0. Which command resolves the issue persistently without disabling SELinux?

Accepted Answer

semanage fcontext -a -t httpd_sys_content_t "/var/www/custom(/.*)?" && restorecon -R /var/www/custom. Option D is correct because it uses `semanage fcontext` to add a persistent file context rule for `/var/www/custom` and its contents, then applies it with `restorecon`. This ensures the `httpd_sys_content_t` type is set persistently across file system relabeling, resolving the 403 error caused by the default SELinux type (`default_t`) that denies Apache access.

Answer

chcon -t httpd_sys_content_t /var/www/custom

Answer

setsebool -P httpd_enable_custom on

Answer

restorecon -R /var/www/custom

Question 15

Refer to the exhibit. A web server must also accept HTTPS traffic on port 8443. Which command should the administrator run to permanently open this port?

Accepted Answer

firewall-cmd --add-port=8443/tcp --permanent && firewall-cmd --reload. The correct command adds port 8443/tcp permanently and reloads the firewall. Option B lacks --permanent and reload. Option C adds the port without --permanent. Option D uses --add-service incorrectly.

Answer

firewall-cmd --add-service=8443/tcp --permanent

Answer

firewall-cmd --add-port=8443/tcp

Answer

firewall-cmd --add-port=8443/tcp --zone=public