1z0-106 Exam Dumps - Oracle Linux Administration Questions and Answers

Understanding AutoFS Behavior:

AutoFSautomatically mounts file systems when accessed and unmounts them after a period of inactivity (default is 5 minutes).

A file system remains mounted as long as it isactive, meaning processes are accessing files or directories within it.

Scenario Analysis:

First Session:

Changed to a directory under AutoFS control (mount point is active).

Second Session:

Changed to /etc (does not affect the first session).

Idle Time Expires:

AutoFS checks for idle mounts to unmount.

Implications:

The mount point remainsactivebecause the shell in the first session is in the AutoFS directory.

AutoFS willnotunmount the file system while it is active.

Oracle Linux Reference:

Oracle® Linux 8: Configuring File Systems-Using the Automounter:

"A file system remains mounted as long as there are open files or directories within it."

Correct Options:

Option B:The file system remains mounted until you log out from the first session.

Option E:The file system remains mounted until you switch to a directory outside the current mount point.

Why Other Options Are Incorrect:

Option A:Incorrect because the mount does not persist indefinitely; it's unmounted when no longer active.

Option C:Incorrect because the mount is still active; the timer does not cause unmounting in this case.

Option D:Incorrect because the second session does not influence the mount status in the first session.

Option B: journalctl -p err shows only error log level.

Explanation:

The -p or --priority option in journalctl filters messages by their priority level.

When specifying asingle priority level, journalctl shows messagesonlyat that level.

The priority levels, as per syslog standards, are:

0: emerg

1: alert

2: crit

3: err

4: warning

5: notice

6: info

7: debug

Therefore, journalctl -p err displays messages with priorityerr (3)only.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onFiltering Output withjournalctl:

"Use the -p option to display messages from the journal that have a specific priority level."

Example:

# journalctl -p err

Option D: journalctl -k shows kernel logs since the last boot.

Explanation:

The -k or --dmesg option filters messages from the kernel, equivalent to the output of the dmesg command.

This option implies -b, which limits the output to messages from the current boot.

Therefore, journalctl -k displays kernel messages since the last boot.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onViewing Kernel Messages:

"Use the journalctl -k command to display kernel messages since the last system boot."

Example:

# journalctl -k

Option E: journalctl -p 6 shows all info log level messages and above.

Explanation:

When specifying a single numeric priority, journalctl displays messages withthat priority level and higher priority levels(i.e., lower severity).

Priority levels are ordered from 0 (highest severity) to 7 (lowest severity).

Therefore, journalctl -p 6 shows messages with priorities:

0 (emerg)

1 (alert)

2 (crit)

3 (err)

4 (warning)

5 (notice)

6 (info)

This includesinfo level messages (6)and all higher priority messages.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onFiltering Output with journalctl:

"When you specify a single priority level, journalctl shows messages at that level and higher severity."

Example:

# journalctl -p 6

Why Other Options Are Not Correct:

Option A:journalctl -bl -p err fails if journal persistence is not configured.

Explanation:

The -b option displays messages from the current boot. This works even if journal persistence isnotconfigured because the logs from the current boot are stored in volatile memory (/run/log/journal).

Therefore, the command doesnot failif journal persistence is not configured.

Oracle Linux Reference:

Oracle® Linux 8: Managing Log Files- Section onJournal Volatility:

"By default, the journal stores logs in volatile memory and does not persist logs across reboots unless persistent storage is configured."

Option C:journalctl -p notice..warning shows all messages from notice to warning log level since the last boot.

Explanation:

The -p option allows specifying arangeof priorities. However, the correct order for the range should be from thehigher priority (lower number)to thelower priority (higher number).

Also, the priorities should be specified in the correct sequence, and ranges are inclusive.

Moreover, journalctl by default shows messages from all boots unless limited by the -b option.

Therefore, without -b, it does not limit messages to "since the last boot," making the statement incorrect.

Correct Command:

To display messages fromwarning (4)tonotice (5), the command should be:

# journalctl -p warning..notice -b

But even then, the priorities need to be specified correctly, and the command in Option C is incorrect.

Conclusion:

OptionsB,D, andEare correct because they accurately describe the behavior of the journalctl command in filtering and displaying log messages based on priority levels and sources.

Option A (Correct):The command creates a Kubernetes Deployment, which ensures the specified number of replicas (pods) are running at all times. The deployment will manage the creation and maintenance of these pods to ensure availability.

Option D (Correct):The deployment configuration specifies that the container running inside the pod exposes port 80 (containerPort: 80).

Option B (Incorrect):The deployment is namednginx-deployment, notnginx.

Option C (Incorrect):The command creates a Deployment object that manages multiple pods; it does not directly create a single pod namednginx.

Option E (Incorrect):The command specifies the nginx image version1.14.2, but it will not fail immediately if the image version is not available. Kubernetes will attempt to pull the image, and the failure will happen during that step if the image does not exist.

Oracle Linux Reference:Refer to:

Kubernetes Documentation on Deployments

kubectl createcommand usage details.

Option B (Correct):Btrfs uses a copy-on-write mechanism for both data and metadata, which ensures that the file system is more resilient to crashes and data corruption.

Option E (Correct):Btrfs supports online resizing, meaning that you can change the size of a mounted Btrfs file system without unmounting it.

Option G (Correct):Btrfs automatically defragments files in the background to maintain performance.

Option A (Incorrect):While Btrfs does support mirroring, it is not strictly block device mirroring in the traditional sense like RAID; it uses a different approach to redundancy.

Option C (Incorrect):Btrfs is not a cluster file system; it is designed for local file systems.

Option D (Incorrect):While Btrfs can store small files efficiently, it is not its primary design goal compared to other file systems optimized specifically for small files.

Option F (Incorrect):Btrfs is a file system with integrated volume management capabilities but is not a general-purpose volume manager like LVM.

Oracle Linux Reference:Refer to:

Oracle® Linux 8: Btrfs File System

man btrfsfor features and management.

Explanation of Answer A:When thechrootcommand is executed with/jail, the environment is changed to use/jailas its new root directory. Inside this environment, only the directories and files copied into/jailare accessible. Since/jaildoes not contain a/rootdirectory, the commandcd(which defaults to changing to the user's home directory) will fail, displayingNo such file or directory. Thepwdcommand shows the root of the chroot environment (/), andlsdisplays the contents of/jail, which includesbinandlib64.

Explanation of Answer D:Theinitramfs(initial RAM filesystem) is a temporary filesystem loaded into memory during the boot process, containing essential drivers and utilities. The kernel usesinitramfsto load necessary drivers and modules required to access the root file system, particularly if it resides on a disk that requires special drivers.

Explanation of Answer E:Both thevmlinuz(the compressed Linux kernel image) and theinitramfsfile are located in the/bootdirectory. The bootloader, such as GRUB, reads these files from/bootto start the system.

Option A (Correct):The configuration lineauthpriv.* /var/log/authwould direct all messages of theauthprivfacility (which includes sensitive authentication messages) to the/var/log/authfile. The log entries provided, which include authentication-related messages from PAM (pam_unix), would be logged due to this setting.

Option B (Incorrect):The*.emerg *setting logs emergency messages to all users, not specifically the provided log output.

Option C (Incorrect):This setting logs various non-authentication-related messages to/var/log/messages. It specifically excludesauthpriv.

Option D (Incorrect):This setting appears to be commented out and incorrect for the logging behavior described.

Option E (Incorrect):Thecron.*setting logs cron messages, unrelated to the provided authentication logs.

Oracle Linux Reference:Refer to:

Oracle® Linux 8: System Logging with rsyslog

Thednf infocommand provides detailed information about an installed package. When used with the path of a binary (such as/usr/bin/gzip), it shows the package that provides the binary along with detailed information like the version, release, architecture, size, source, repository, summary, URL, and license.

Explanation of Answer A:The commandfirewall-cmd --zone=public --add-service=cockpit --permanentadds the Cockpit service to the public zone permanently. This means that the service is explicitly allowed only within the public zone, not in any other zones.

Explanation of Answer C:Using the--permanentflag withfirewall-cmdcommands ensures that the changes are stored in the firewalld configuration and are persistent across reboots. Therefore, when thefirewalldservice restarts or the system reboots, the runtime configuration will not be lost, and the changes will remain in effect.

Explanation of Answer C:Thesscommand can be used to display all available internal TCP information, including established connections with detailed TCP metrics, which matches the output in Answer C.

Explanation of Answer D:Thesscommand can display listening ports (TCP in this case) with details like congestion control algorithms (cubic), which aligns with Answer D. The output indicates a listening TCP socket on port 80.