EX200 Practice Exam 4 — 20 Questions

Question 1

The administrator wants to reduce the file system size to 40GB. Which command sequence should be used?

Accepted Answer

It is not possible to shrink an XFS file system. XFS is a high-performance 64-bit journaling file system that does not support online or offline shrinking. Once an XFS file system is created, its size cannot be reduced; the only way to reclaim space is to back up the data, destroy the file system, recreate it at the desired size, and restore the data. Therefore, any attempt to shrink an XFS file system using lvreduce or similar tools will corrupt the file system.

Answer

xfs_repair; lvreduce

Answer

umount /mnt/data; lvreduce -L 40G; mount; xfs_growfs

Answer

lvreduce -L 40G /dev/vg00/lvol0; xfs_growfs

Question 2

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. The log shows 'no matching host key type found. Their offer: ssh-rsa'. This indicates the client offered an ssh-rsa host key, but the server's configuration (likely via the `HostKeyAlgorithms` directive in `/etc/ssh/sshd_config`) does not include ssh-rsa. In modern OpenSSH (e.g., RHEL 8/9), ssh-rsa is often disabled by default due to its reliance on SHA-1, which is considered weak. The server requires a different host key type (e.g., rsa-sha2-256, rsa-sha2-512, or ecdsa-sha2-nistp256), causing the connection to fail before authentication even begins.

Answer

The server's firewall is blocking the connection

Answer

The SSH service is not running

Answer

The client's IP is blacklisted

Question 3

A file has been assigned an incorrect SELinux context, preventing a service from accessing it. Which command restores the default SELinux context for that file?

Accepted Answer

restorecon. The `restorecon` command is used to restore the default SELinux security context for a file or directory based on the system's policy store (the file_contexts database). When a file has an incorrect context that prevents a service from accessing it, `restorecon` resets the context to the correct default, allowing the service to access the resource as intended.

Answer

chcon

Answer

fixfiles

Answer

setfiles

Question 4

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 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 5

A Red Hat Enterprise Linux 8 system was recently updated via 'yum update'. After reboot, the systemd-logind service fails to start with the error 'Failed to start Login Service' and 'Permission denied' messages in the journal. The administrator checks the SELinux status with 'getenforce' and it returns 'Enforcing'. The administrator also notices that the '/var/run' directory is now a symlink to '/run'. There are no firewall issues. The service works if SELinux is set to permissive. Which single action should the administrator take to resolve this issue permanently?

Accepted Answer

Run 'restorecon -Rv /run' to restore default SELinux contexts for /run. After a yum update, SELinux contexts on /run may be incorrect because /var/run is a symlink to /run. When SELinux is enforcing, systemd-logind requires the correct context (typically system_u:object_r:var_run_t:s0) on /run to access its runtime files. Running 'restorecon -Rv /run' restores the default SELinux contexts for all files under /run, resolving the 'Permission denied' errors permanently without disabling SELinux.

Answer

Add 'selinux=0' to kernel boot parameters and reboot

Answer

Edit the systemd-logind service unit to add 'Permissions=yes'

Answer

Reinstall the systemd-logind package using 'yum reinstall systemd'

Question 6

A server has a requirement that all users in the 'finance' group must have a password aging policy that forces password change every 90 days. Which approach best achieves this for existing users?

Accepted Answer

Write a script to run 'chage -M 90' for each user in the finance group. `chage -M 90` sets the maximum password age for a specific user, and by scripting it to apply to all members of the 'finance' group, you directly enforce the 90-day policy on existing users. This approach works regardless of the default settings in `/etc/login.defs`, which only affect new users, and avoids the manual and error-prone editing of `/etc/shadow`.

Answer

Set PASS_MAX_DAYS 90 in /etc/login.defs

Answer

Edit /etc/shadow and change the fifth field for all users

Answer

Configure pam_pwquality.so to enforce password age

Question 7

An administrator attempts to mount an XFS filesystem from /dev/sdc1 to /mnt/archive but receives the error: 'mount: /mnt/archive: wrong fs type, bad option, bad superblock on /dev/sdc1, missing codepage or helper program, or other error.' The output of 'dumpe2fs /dev/sdc1' shows 'dumpe2fs: Bad magic number in super-block while trying to open /dev/sdc1'. What is the most likely problem?

Accepted Answer

The filesystem on /dev/sdc1 is XFS, not ext4. The error message 'wrong fs type' combined with 'dumpe2fs: Bad magic number in super-block' indicates that the filesystem on /dev/sdc1 is not an ext2/3/4 filesystem. dumpe2fs is designed to read ext2/3/4 superblocks, and the 'bad magic number' error means it cannot find a valid ext superblock. Since the administrator is trying to mount an XFS filesystem, the correct tool to examine it is xfs_db or xfs_info, not dumpe2fs. Therefore, the most likely problem is that the filesystem is XFS, not ext4.

Answer

The mount point /mnt/archive does not exist

Answer

The XFS kernel module is not loaded

Answer

The partition /dev/sdc1 does not exist

Question 8

A system administrator notices that a server is responding slowly. The administrator runs `top` and sees a process named `backup_script` consuming 95% CPU. The process runs as root and is supposed to run nightly backups. However, the system load average is low. The administrator wants to investigate without killing the process. Which of the following is the best course of action?

Accepted Answer

Use `renice -n 19 -p ` to lower the priority of the process.. `renice -n 19 -p ` lowers the CPU scheduling priority of the running `backup_script` process to the lowest possible value (19), which reduces its CPU consumption without killing it. This allows the administrator to investigate the cause of the high CPU usage while minimizing the impact on other processes and system responsiveness.

Answer

Use `nice -n 19 ./backup_script` to start the process with lower priority next time.

Answer

Use `chrt -i 0 <PID>` to set the scheduling policy to idle.

Answer

Use `kill -STOP <PID>` to pause the process and then resume later.

Question 9

An administrator notices that the /tmp directory is filling up quickly. They want to find all files in /tmp that are larger than 100 MB and owned by user 'ftp', then delete them. The administrator runs: find /tmp -type f -size 100M -user ftp -exec rm {} \;. However, this command deletes only files that are exactly 100 MB, not larger. Which find expression should be used instead?

Accepted Answer

find /tmp -type f -size +100M -user ftp -exec rm {} \;. The `find` command uses `+` before a size value to match files larger than that size, not exactly equal. The original command omitted the `+`, so it matched only files exactly 100 MB. Adding `+100M` correctly selects files larger than 100 MB.

Answer

find /tmp -type f -size 100M -user ftp -exec rm {} \;

Answer

find /tmp -type f -size +100M ! -size 100M -user ftp -exec rm {} \;

Answer

find /tmp -type f -size +100M -size -100M -user ftp -exec rm {} \;

Question 10

A company runs a critical web application in a container on a Red Hat Enterprise Linux 9 server. The container is started via a systemd service called 'webapp.service'. The service unit file was generated using 'podman generate systemd --new --name webapp'. Recently, after a kernel update and reboot, the service fails to start the container. The administrator runs 'systemctl status webapp.service' and sees 'Active: failed (Result: exit-code)' and 'Process: 1234 ExecStart=/usr/bin/podman run ... (code=exited, status=125)'. The administrator also checks 'journalctl -u webapp.service' and sees: 'Error: unable to start container: container create failed: OCI runtime error: container_linux.go:380: starting container process caused: exec: "/usr/bin/app.sh": stat /usr/bin/app.sh: no such file or directory'. The container image was built locally using a Containerfile that includes 'COPY app.sh /usr/bin/app.sh'. The administrator verifies the image is present locally. What should the administrator do to resolve this issue?

Accepted Answer

Rebuild the container image using 'podman build -t webapp .' to ensure the app.sh file is included, then restart the service.. The error indicates that the container image is missing the `/usr/bin/app.sh` file, even though the `COPY` instruction was in the Containerfile. The most likely cause is that the image was built before the `app.sh` script was added to the build context, or the build was incomplete. Rebuilding the image with `podman build -t webapp .` ensures the file is properly included in the image layers, resolving the OCI runtime error.

Answer

Disable SELinux with setenforce 0 and restart the service.

Answer

Remove the systemd service and regenerate it with 'podman generate systemd --new --name webapp'.

Answer

Manually create the /usr/bin/app.sh file inside the container using podman exec.

Question 11

Based on the exhibit, which command should be used to start the container named 'mycontainer'?

Accepted Answer

podman start mycontainer. The correct command to start an existing but stopped container is 'podman start mycontainer'. 'podman start' resumes a container that has been created (via 'podman create') or previously stopped, without creating a new instance. Option D is correct because it directly addresses the requirement to start the container named 'mycontainer' that already exists.

Answer

podman attach mycontainer

Answer

podman restart mycontainer

Answer

podman run mycontainer

Question 12

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

Accepted Answer

systemctl status crond. On RHEL-based systems (including Red Hat Enterprise Linux, CentOS, and Fedora), the cron daemon is named `crond`, not `cron`. The `systemctl status crond` command checks whether the `crond` service is active, enabled, and running. This is the correct method for verifying the cron daemon's status on systems using systemd.

Answer

systemctl status cron

Answer

systemctl list-units --type=service

Answer

service crond status

Question 13

A user wants to run a container that will restart automatically unless explicitly stopped by the administrator. Which podman run option should be used?

Accepted Answer

--restart=unless-stopped. The `--restart=unless-stopped` policy ensures the container restarts automatically whenever it exits, unless the administrator explicitly stops it with `podman stop`. This matches the requirement exactly: the container will keep restarting even after system reboots or crashes, but will not restart if the admin manually stops it. The other policies either do not restart on manual stop (`always`) or only restart on non-zero exit codes (`on-failure`).

Answer

--restart=on-failure

Answer

--restart=always

Answer

--restart=no

Question 14

An administrator wants to add an additional swap partition of 2GB on device /dev/sdb1. Which set of commands should be used to enable swap and make it persistent across reboots?

Accepted Answer

mkswap /dev/sdb1; swapon /dev/sdb1; echo '/dev/sdb1 swap swap defaults 0 0' >> /etc/fstab. It follows the proper sequence to prepare and activate a swap partition on /dev/sdb1. First, `mkswap` initializes the partition as a swap area by writing a swap signature. Then `swapon` activates it immediately. Finally, adding an entry to /etc/fstab ensures the swap is automatically enabled at boot, making it persistent across reboots.

Answer

parted /dev/sdb set 1 swap on

Answer

swapadd /dev/sdb1

Answer

mkfs.ext4 /dev/sdb1; mount /dev/sdb1 /swap

Answer

None of the above

Question 15

A system fails to boot because of a corrupted fstab file. The administrator boots into rescue mode from a RHEL installation ISO. Which command should be run first to mount the root filesystem read-write?

Accepted Answer

mount /dev/mapper/rhel-root /mnt/sysimage. In rescue mode, the root filesystem is not mounted by default. The first step is to mount the logical volume containing the root filesystem (e.g., /dev/mapper/rhel-root) to a temporary mount point like /mnt/sysimage so that you can access and repair the corrupted /etc/fstab file. Option A correctly uses the mount command with the device and mount point, which is the standard procedure for RHEL rescue environments.

Answer

mount -o rw,remount /sysroot

Answer

chroot /mnt/sysimage

Answer

systemctl rescue

Question 16

A junior system administrator configures rsyslog on a RHEL 9 server to forward logs to a remote centralized log server. They add the line *.* @192.168.1.100:514 to /etc/rsyslog.conf and restart rsyslog with systemctl restart rsyslog. Local logging works fine, but the remote server does not receive any logs. The administrator checks the local firewall and confirms that UDP port 514 is open outbound. They also verify network connectivity using nc. What is the most likely cause?

Accepted Answer

The SELinux boolean rsyslog_remote is disabled, blocking outbound syslog.. On RHEL 9, SELinux enforces a targeted policy that blocks rsyslog from making outbound network connections by default. The boolean `rsyslog_remote` controls this behavior; when disabled, SELinux denies the outbound syslog traffic even though the local firewall allows it. The administrator must enable this boolean with `setsebool -P rsyslog_remote on` to allow rsyslog to forward logs via UDP or TCP.

Answer

The systemd unit for rsyslog is masked, preventing it from running.

Answer

The remote rsyslog server is not listening on UDP port 514.

Answer

The configuration should use @@ for TCP instead of @ for UDP.

Question 17

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 18

An administrator needs to configure a service to start automatically at boot and also start it immediately without rebooting. Which single command accomplishes both tasks?

Accepted Answer

systemctl enable --now httpd.service. `systemctl enable --now httpd.service` combines the `enable` action (creating symlinks for automatic start at boot) with the `start` action (immediately launching the service) in a single command. This is the precise method in systemd to achieve both goals without rebooting.

Answer

systemctl start httpd.service

Answer

systemctl enable httpd.service

Answer

systemctl reenable httpd.service

Question 19

Which TWO commands are valid for resizing an XFS file system? (Choose exactly two.)

Accepted Answer

xfs_growfs /mnt. `xfs_growfs` is the dedicated command for resizing (growing) an XFS file system while it is mounted. It expands the file system to fill the available space in the underlying device or logical volume, making it the primary tool for XFS resizing operations.

Answer

xfs_admin -L /mnt

Answer

resize2fs /dev/sda1

Answer

xfs_repair /dev/sda1

Question 20

An administrator wants to change the default systemd target to multi-user.target. Which three steps are part of a correct procedure? (Choose three.)

Accepted Answer

systemctl isolate multi-user.target. `systemctl isolate multi-user.target` immediately switches the current systemd target to multi-user.target, which is the correct way to change the active target at runtime without a reboot. This command stops all units not required by the new target and starts those that are, effectively changing the system's operational state.

Answer

systemctl enable multi-user.target

Answer

systemctl start multi-user.target