XK0-006 Practice Exam 51 — 20 Questions

Question 1

A server with multiple disks is configured with RAID 5 for performance and redundancy. The administrator notices that write performance is lower than expected. Which RAID level would provide better write performance while still offering fault tolerance with the same number of disks (minimum 4)?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

RAID 10. RAID 10 (striping of mirrors) provides better write performance than RAID 5 because it does not incur the overhead of calculating and writing parity data on every write operation. With a minimum of four disks, RAID 10 offers fault tolerance (each mirror can survive one disk failure) while delivering the full write speed of the underlying disks, unlike RAID 5 which must update parity across all disks.

Answer

RAID 0

Answer

RAID 6

Answer

RAID 1

Question 2

An administrator is configuring log rotation for /var/log/auth.log. They want logs to be rotated weekly, compressed, and kept for 12 weeks. Which logrotate configuration directive achieves this?

Accepted Answer

weekly { rotate 12 compress }. weekly, compress, and rotate 12 set the desired behavior. The other options have incorrect parameters.

Answer

daily { rotate 12 compress }

Answer

weekly { rotate 52 compress }

Answer

monthly { rotate 12 compress }

Question 3

An administrator wants to generate a self-signed certificate and private key for testing. Which command creates both in one step?

Accepted Answer

openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes. The `openssl req -x509 -newkey rsa:2048` command generates a new private key (via `-newkey`) and immediately creates a self-signed X.509 certificate (via `-x509`) in a single step. The `-keyout` and `-out` flags specify the output files for the private key and certificate, respectively, and `-nodes` ensures the private key is not encrypted with a passphrase, which is typical for testing scenarios.

Answer

openssl genrsa -out key.pem 2048

Answer

openssl req -new -x509 -days 365 -key key.pem -out cert.pem

Answer

openssl x509 -req -in req.pem -signkey key.pem -out cert.pem

Question 4

An administrator runs 'mount -a' and receives the error shown in the exhibit. The /home partition was recently removed and replaced with a new disk. Which of the following steps should the administrator take to resolve the issue?

Accepted Answer

Run 'blkid /dev/sda3' to find the new UUID and update /etc/fstab.. The error occurs because the /home partition was replaced with a new disk, so its UUID (or device identifier) in /etc/fstab no longer matches the actual disk. Running 'blkid /dev/sda3' retrieves the new UUID, which must then be updated in /etc/fstab so that 'mount -a' can mount the correct device automatically.

Answer

Run 'mount /dev/sda3 /home' to mount the partition manually.

Answer

Run 'fsck /dev/sda3' to check the filesystem.

Answer

Run 'mkfs.ext4 /dev/sda3' to create a new filesystem.

Question 5

A user runs a command and receives the error 'bash: myapp: command not found'. The administrator confirms the binary exists in /usr/local/bin. Which environment variable should be checked?

Accepted Answer

PATH. The 'command not found' error indicates that the shell cannot locate the executable in any of the directories listed in the PATH environment variable. Even though the binary exists in /usr/local/bin, if that directory is not in PATH, the shell will not find it. Checking and correcting the PATH variable to include /usr/local/bin will resolve the issue.

Answer

HOME

Answer

SHELL

Answer

LD_LIBRARY_PATH

Question 6

A Linux server experiences intermittent network connectivity issues. The administrator suspects a duplex mismatch. Which tool can best confirm duplex and speed settings on a network interface?

Accepted Answer

ethtool eth0. `ethtool eth0` is the standard Linux utility for querying and controlling network interface driver and hardware settings, including negotiated speed and duplex mode. It directly displays the current link status, speed (e.g., 1000Mb/s), and duplex (full/half), making it the best tool to confirm a duplex mismatch.

Answer

mii-tool eth0

Answer

dmesg | grep eth0

Answer

ip link show eth0

Question 7

Which TWO conditions must be met for a user to successfully delete a file owned by a different user in a directory? (Choose two.)

Accepted Answer

The user has write permission on the directory. To delete a file in Linux, the user does not need any permissions on the file itself; instead, the user needs write permission on the directory because deleting a file modifies the directory's contents (removing the directory entry). Additionally, execute permission on the directory is required to access the directory and its inode entries, allowing the user to traverse the directory to locate the file. These two permissions together enable the deletion of a file owned by another user.

Answer

The user has write permission on the file

Answer

The user is the owner of the file

Answer

The user is a member of the group that owns the directory

Question 8

After using 'apt-get install' to install several packages, the administrator notices that disk space is low. Which command cleans up the package cache?

Accepted Answer

apt-get clean. The 'apt-get clean' command removes all package files (.deb) from the local cache located in /var/cache/apt/archives/. This frees up disk space without affecting installed packages, as the cache is only used for future installations or reinstallations. It is the correct command to clean up the package cache after installations.

Answer

apt-get purge

Answer

apt-get autoremove

Answer

apt-get remove

Question 9

After configuring AppArmor, an administrator wants to verify the status of all profiles and switch a profile from complain to enforce mode. Which TWO commands are appropriate? (Choose two.)

Accepted Answer

aa-status. B is correct because `aa-status` displays the current status of all AppArmor profiles, allowing the administrator to verify which are in enforce or complain mode. E is correct because `aa-enforce` switches a profile to enforce mode, which is the required action. A is incorrect; restarting the AppArmor service does not verify status or switch a profile's mode. C is incorrect; `apparmor_parser -r` reloads profile definitions from disk, but does not change the mode of a profile; mode is changed via `aa-enforce` or `aa-complain`. D is incorrect because `aa-complain` sets the profile to complain mode, which is the opposite of the desired enforce mode.

Answer

systemctl restart apparmor

Answer

apparmor_parser -r /etc/apparmor.d/profile

Answer

aa-complain /path/to/profile

Question 10

A technician needs to generate a self-signed certificate for an internal web server. Which OpenSSL command creates a new private key and a certificate signing request (CSR) in one step?

Accepted Answer

openssl req -new -newkey rsa:2048 -nodes -keyout server.key -out server.csr. openssl req -new -newkey rsa:2048 -nodes -keyout server.key -out server.csr creates both key and CSR.

Answer

openssl req -x509 -newkey rsa:2048 -nodes -keyout server.key -out server.crt

Answer

openssl genrsa -out server.key 2048 && openssl req -new -key server.key -out server.csr

Answer

openssl ca -new -key server.key -out server.csr

Question 11

A system administrator needs to configure a Linux server to automatically synchronize time with the NTP pool servers. The server should also act as an NTP peer for other servers on the local network. Which file should be modified, and which directive should be added?

Accepted Answer

/etc/chrony/chrony.conf with "pool pool.ntp.org iburst" and "allow 192.168.1.0/24". The system uses chrony (the default NTP implementation on modern RHEL/CentOS 8+ and many other distributions). The `pool` directive with `iburst` synchronizes time from NTP pool servers, and the `allow` directive grants local subnet peers access to the chronyd service, enabling the server to act as an NTP peer for other hosts on 192.168.1.0/24.

Answer

/etc/npt.conf with "peer pool.ntp.org"

Answer

/etc/systemd/timesyncd.conf with "NTP=pool.ntp.org" and "LocalPort=123"

Answer

/etc/ntp.conf with "server pool.ntp.org iburst"

Question 12

During boot, a Linux system displays a kernel panic with the message 'VFS: Unable to mount root fs on unknown-block(0,0)'. Which of the following is the most likely cause?

Accepted Answer

Corrupted initramfs missing necessary storage drivers. The error 'VFS: Unable to mount root fs on unknown-block(0,0)' indicates the kernel cannot locate or access the root filesystem. This is most commonly caused by a corrupted or missing initramfs that lacks the necessary storage drivers (e.g., for SATA, NVMe, or LVM) to communicate with the root device. Without these drivers, the kernel cannot read the root filesystem, resulting in a panic.

Answer

Incorrect GRUB timeout setting

Answer

A faulty RAM module causing memory errors

Answer

Filesystem corruption on the boot partition

Question 13

Match each SELinux context component to its description.

Accepted Answer

user: An SELinux user identity that is authorized for a role.. SELinux contexts are structured as user:role:type:level. The user identifies the SELinux user, role defines accessible types, type controls access, and level specifies sensitivity. Common confusions involve swapping user and type definitions.

Answer

user: The security context for processes (domain) and objects.

Answer

type: An SELinux user identity that is authorized for a role.

Question 14

A security analyst wants to ensure that users cannot change their password more than once every 7 days. Which command and option should be used to enforce this policy for user 'jsmith'?

Accepted Answer

chage -m 7 jsmith. The `chage -m 7 jsmith` command sets the minimum number of days required between password changes for user jsmith to 7 days. The `-m` option of `chage` specifically controls the minimum password age, preventing the user from changing their password more than once every 7 days.

Answer

usermod -e 7 jsmith

Answer

chage -M 7 jsmith

Answer

passwd -n 7 jsmith

Question 15

A file server running RHEL 8 uses NFS to export directories. Clients report that they cannot mount an NFS share. The server's firewall is configured but NFS-related services are enabled. The administrator checks `exportfs -v` and sees the export is listed. Which service must be added to the firewall to allow NFS?

Accepted Answer

nfs. NFS on RHEL 8 requires the 'nfs' service to be added to the firewall to allow incoming NFS traffic. The 'nfs' service in firewalld opens TCP and UDP ports 2049, which is the standard port for NFSv4. Even though NFS-related services are enabled, the firewall must explicitly permit this port for clients to mount the share.

Answer

rpc-bind

Answer

samba

Answer

mountd

Question 16

A technician needs to remove all files in /tmp that are owned by the user 'jdoe' and have not been accessed in 10 days. Which THREE commands or options would be part of a correct solution? (Select THREE.)

Accepted Answer

find /tmp -user jdoe -atime +10 -exec rm {} \;. find /tmp -user jdoe -atime +10 -delete finds files belonging to jdoe, with last access more than 10 days ago, and deletes them. -atime measures access time. -delete is a direct action. Alternatively, using -exec rm {} \; works. The correct components include the path, -user, -atime, and action.

Answer

find /tmp -user jdoe -delete

Answer

find /tmp -user jdoe -mtime +10

Question 17

A developer is writing a Bash script that needs to test whether a file exists and is readable. Which of the following conditionals correctly performs this check?

Accepted Answer

if [[ -f $file && -r $file ]]; then. The -f test checks for a regular file, and -r checks if it is readable. Both must be true, so they are combined with &&.

Answer

if test -f $file || test -r $file; then

Answer

if [ -f $file -a -r $file ]; then

Answer

if [ -f $file -o -r $file ]; then

Question 18

An administrator modified kernel parameters in /etc/sysctl.conf. Which command applies the changes without rebooting?

Accepted Answer

sysctl -p. The `sysctl -p` command reads the settings from `/etc/sysctl.conf` and applies them immediately to the running kernel without requiring a reboot. This is the standard method for reloading persistent kernel parameter changes on Linux systems.

Answer

sysctl -w

Answer

sysctl -r

Answer

sysctl -a

Question 19

Refer to the exhibit. A user reports that they cannot write to /data, receiving a 'No space left on device' error. However, the df output shows 5.2G available. What is the most likely cause?

Accepted Answer

The filesystem is out of inodes.. The 'No space left on device' error despite 5.2G available space indicates the filesystem has run out of inodes. Inodes store metadata about files, and when exhausted, no new files can be created even if free space exists. This is common in filesystems with many small files. Option C is correct. Option A is incorrect because fstab is configured correctly; the filesystem is mounted. Option B is incorrect because the mount options do not include 'ro' (read-only). Option D is incorrect because the UUID has not changed; the partition is accessible.

Answer

The /data entry in fstab is incorrect, causing the mount to fail.

Answer

The partition is mounted read-only.

Answer

The UUID for /data has changed.

Question 20

A system administrator needs to ensure that the Apache HTTP server starts automatically at boot and is started immediately without rebooting. Which command accomplishes both tasks?

Accepted Answer

systemctl enable --now httpd. The `systemctl enable --now httpd` command combines two actions: it creates the necessary symlinks to start the Apache HTTP server automatically at boot (enable) and immediately starts the service without rebooting (start). The `--now` flag is the key to performing both tasks in a single command, fulfilling the requirement exactly.

Answer

systemctl disable --now httpd

Answer

systemctl enable httpd

Answer

systemctl start httpd