XK0-006 Practice Test 41 — 15 Questions

Question 1

The system is experiencing slow disk I/O. Based on the exhibit, which step should the administrator take to improve performance?

Accepted Answer

Add the 'noatime' mount option in /etc/fstab. The 'noatime' mount option disables updating the access time (atime) on every file read, which eliminates a significant source of metadata write operations. Since the exhibit indicates slow disk I/O, reducing unnecessary writes directly improves performance by freeing I/O bandwidth for actual data transfers. This is a standard, low-risk optimization for workloads where access timestamps are not required.

Answer

Increase the filesystem block size

Answer

Enable write-back caching on the drive using hdparm

Answer

Change the I/O scheduler to 'deadline'

Question 2

A junior administrator reports that users cannot connect to a file server running Samba. The server is reachable via ping. Logs from the Samba service show: 'smbd: error while loading shared libraries: libgnutls.so.30: cannot open shared object file: No such file or directory'. The administrator confirms the package 'libgnutls' is installed. Which of the following is the most likely cause and solution?

Accepted Answer

The library path is not set; run ldconfig.. The error 'cannot open shared object file' indicates that the dynamic linker cannot find the libgnutls.so.30 library at runtime, even though the libgnutls package is installed. Running `ldconfig` updates the linker cache, which rebuilds the mapping of shared library names to their actual file paths, resolving the missing library reference for Samba.

Answer

The system libraries are out of sync; run apt-get update.

Answer

The Samba package is corrupted; reinstall Samba.

Answer

The Samba service is not running; restart it.

Question 3

An organization uses Kubernetes to deploy containerized applications. A pod fails to start with an ImagePullBackOff error. What is the most likely cause?

Accepted Answer

The image name is misspelled or does not exist in the registry. The ImagePullBackOff error in Kubernetes indicates that the kubelet is unable to pull the container image from the specified registry. The most common cause is a misspelled image name or a non-existent image in the registry, which prevents the container runtime from fetching the image. This triggers a back-off mechanism where the kubelet retries the pull with increasing delays.

Answer

The pod exceeded its memory limit

Answer

The container port is already in use

Answer

The node is out of disk space

Question 4

A Kubernetes administrator needs to expose a deployment externally using a Service. Which THREE of the following Service types can be used? (Select THREE).

Accepted Answer

ClusterIP. ClusterIP, LoadBalancer, and NodePort are the three Kubernetes Service types that can be used to expose a deployment externally. ClusterIP alone is internal, but when combined with an Ingress controller, it provides external access by routing traffic from outside the cluster to the Service. LoadBalancer provisions an external load balancer with a public IP. NodePort opens a static port on every node's IP, allowing external traffic. ExternalName (option C) does not expose the deployment; it only maps a Service to an external DNS name, so it is not a valid choice for exposing a deployment externally.

Answer

ExternalName

Answer

Ingress

Question 5

After a kernel update, loading a proprietary kernel module fails with 'Invalid module format'. The module was built from source against the previous kernel. What is the most likely cause?

Accepted Answer

Module was not rebuilt for the new kernel version. The 'Invalid module format' error occurs when a kernel module's version magic string does not match the running kernel's version. Since the module was built against the previous kernel, it contains version information for that older kernel, and the new kernel rejects it as incompatible. Rebuilding the module against the new kernel's headers resolves this mismatch.

Answer

Module is not signed while Secure Boot is enabled

Answer

Module file permissions are incorrect

Answer

SELinux is blocking the module load

Question 6

Which THREE methods are valid for setting the default systemd target (runlevel) to multi-user mode? (Choose three.)

Accepted Answer

systemctl set-default multi-user.target. `systemctl set-default multi-user.target` is the standard systemd command to permanently change the default boot target to multi-user mode (runlevel 3). This command updates the symlink at `/etc/systemd/system/default.target` to point to `/lib/systemd/system/multi-user.target`, ensuring the system boots into a non-graphical, multi-user state.

Answer

Run telinit 3

Answer

Edit /etc/inittab

Question 7

A Linux administrator notices that the system’s disk I/O performance has degraded significantly. Running 'iostat -x 1' shows high %util values on /dev/sda, but low await. Which of the following is the most likely issue?

Accepted Answer

There are many concurrent I/O requests (high queue depth).. High %util with low await indicates that the device is busy processing many concurrent I/O requests, but each request completes quickly. This is characteristic of a high queue depth where the disk is saturated with parallel requests, not that individual requests are slow. The low await confirms that the disk itself is responding fast, so the bottleneck is the volume of simultaneous I/O, not latency per request.

Answer

The filesystem is nearly full.

Answer

The disk cable is loose or faulty.

Answer

The disk is failing and needs replacement.

Question 8

A security audit reveals that a server's /etc/shadow file is readable by all users. Which command would correctly fix the permissions?

Accepted Answer

chmod 600 /etc/shadow. The correct command is 'chmod 600 /etc/shadow' (option B). The /etc/shadow file should only be readable by the root user, as it contains password hashes. Permission 600 grants read and write access only to the owner (root). Option A (644) would allow world read access, which is insecure. Option C (640) would allow group read access, which is also not recommended. Option D includes an unnecessary chown command and uses 640 permissions.

Answer

chmod 644 /etc/shadow

Answer

chmod 640 /etc/shadow

Answer

chmod 640 /etc/shadow && chown root:shadow

Question 9

After a power failure, a Linux server boots into emergency mode. The system logs indicate an unclean filesystem on /dev/sda2. Which command should the administrator run to repair the filesystem?

Accepted Answer

fsck -f /dev/sda2. After a power failure, the system logs indicate an unclean filesystem on /dev/sda2, meaning the filesystem was not properly unmounted and may contain inconsistencies. The `fsck -f /dev/sda2` command forces a filesystem check even if the filesystem appears clean, which is necessary to repair corruption on ext2/ext3/ext4 filesystems. This is the standard tool for checking and repairing such filesystems after an unclean shutdown.

Answer

badblocks /dev/sda2

Answer

xfs_repair /dev/sda2

Answer

mount -o remount,ro /

Question 10

A developer is writing a Bash script that must be portable across different Linux distributions. The script needs to check if a package is installed. Which command should be used to achieve this portability?

Accepted Answer

command -v package. The `command -v package` command is the most portable way to check if a package is installed across different Linux distributions because it uses the POSIX-standard `command` shell built-in, which works in any Bourne-compatible shell (bash, sh, dash, etc.) regardless of the underlying package manager. It returns the path to the executable if the package's binary is in the PATH, or nothing if it is not installed, making it distribution-agnostic.

Answer

which package

Answer

dpkg -l package

Answer

rpm -q package

Question 11

A security audit reveals that the system's PAM configuration does not enforce password complexity. Which PAM module and configuration line should be added to /etc/pam.d/common-password to require at least one uppercase letter, one digit, and a minimum length of 12 characters?

Accepted Answer

password requisite pam_pwquality.so minlen=12 ucredit=-1 dcredit=-1. pam_pwquality is the module for password complexity. The options ucredit=-1, dcredit=-1, minlen=12 enforce the requirements. pam_unix handles password hashing, pam_faillock handles lockout, and pam_cracklib is an older module (deprecated in favor of pam_pwquality).

Answer

password sufficient pam_faillock.so minlen=12 ucredit=-1 dcredit=-1

Answer

password required pam_cracklib.so minlen=12 ucredit=-1 dcredit=-1

Answer

password required pam_unix.so minlen=12 ucredit=-1 dcredit=-1

Question 12

A technician needs to trace the system calls made by a running process to debug a performance issue. Which tool should be used?

Accepted Answer

strace -p PID. `strace -p PID` intercepts and records system calls (kernel-level operations like file I/O, network, and process control) made by a running process, which is exactly what is needed to trace system calls for debugging performance issues. The `-p` flag attaches strace to an existing process by its PID, allowing real-time monitoring of kernel interactions.

Answer

gdb -p PID

Answer

lsof -p PID

Answer

ltrace -p PID

Question 13

A Red Hat Enterprise Linux 8 system is configured with SELinux in enforcing mode. A custom application needs to write to a file in /var/log. The audit log shows an AVC denial for httpd_t attempting to write to var_log_t. Which of the following is the most appropriate persistent solution?

Accepted Answer

Use semanage fcontext to define the default context for the file and then restorecon.. Semanage fcontext defines a persistent default SELinux file context rule, which survives file system relabeling. After defining the rule, restorecon applies the context to the file. This ensures the custom application's log file is labeled httpd_log_t, allowing httpd_t to write to it, while chcon (option C) only makes a temporary change that can be overwritten by restorecon or a relabel.

Answer

Set the SELinux boolean httpd_can_network_connect to on.

Answer

Change the ownership of the file to apache.

Answer

Use chcon to set the file context to httpd_log_t.

Question 14

A user on a workstation with IP 192.168.1.100 reports being unable to SSH to the server with IP 10.0.0.5. Based on the exhibit, what is the most likely cause?

Accepted Answer

The SSH rule only accepts connections from the 10.0.0.0/8 subnet.. The exhibit shows an iptables ruleset where the SSH rule (port 22) explicitly matches the source address 10.0.0.0/8. The workstation has IP 192.168.1.100, which does not fall within the 10.0.0.0/8 range, so the SSH rule will not match. Since no other rule allows SSH, the packet will be evaluated against the default INPUT policy, which is ACCEPT (not shown as DROP), but the SSH rule itself restricts the source, making it unreachable for this client.

Answer

The default INPUT policy is DROP and there is no SSH rule.

Answer

The SSH rule appears after a LOG rule, causing it to be unreachable.

Answer

The SSH port is not allowed in any rule.

Question 15

A company policy requires that only the root user can schedule cron jobs. Which configuration ensures this?

Accepted Answer

Create /etc/cron.allow with only 'root'. The /etc/cron.allow file explicitly lists users who are permitted to schedule cron jobs. When this file exists, only users listed in it can use crontab, and all others are denied — even if /etc/cron.deny exists. By placing only 'root' in /etc/cron.allow, the policy that only root can schedule cron jobs is enforced.

Answer

Add 'root' to /etc/crontab

Answer

Set /usr/bin/crontab permissions to 700

Answer

Add all non-root users to /etc/cron.deny