1z0-106 Exam Dumps - Oracle Linux 8 Advanced System Administration

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.

The commandcryptsetup luksOpen /dev/xvdd1 cryptfsis used to open an encrypted LUKS partition. This command maps the encrypted block device/dev/xvdd1to a decrypted block device that is accessible under/dev/mapper/cryptfs.

Option A (Correct):This is correct because thecryptsetup luksOpencommand creates a device mapping under/dev/mapper/with the name specified (cryptfsin this case). This mapping allows you to access the encrypted content of/dev/xvdd1through the decrypted virtual device/dev/mapper/cryptfs.

Options B, C, D, E (Incorrect):These options are incorrect because they do not accurately reflect the standard behavior of thecryptsetup luksOpencommand. The device created will always be in the format/dev/mapper/whereis the alias specified in the command.

Oracle Linux Reference:For more information, refer to:

Oracle® Linux 8: Managing Storage Devices

man cryptsetupfor more details on theluksOpencommand and LUKS management.

The correct command to create a RAID-1 device (mirroring) consisting of two block volumes with one spare device is optionC:mdadm –create /dev/md0 –level=1 –raid-devices=2 /dev/xvdd1 /dev/xvdd2 –spare-devices=1 /dev/xvdd3.

RAID Level 1:RAID-1, also known as mirroring, involves creating an exact copy (or mirror) of a set of data on two or more disks. This ensures data redundancy; if one disk fails, the other can still provide the data.

mdadm Command Structure:Themdadmcommand is used to manage and monitor RAID devices on Linux. To create a new RAID array, the--createoption is used, followed by several parameters:

/dev/md0: The name of the RAID device to be created.

--level=1: Specifies RAID level 1 (mirroring).

--raid-devices=2: Indicates the number of active devices (two in this case) to be used in the RAID array.

/dev/xvdd1 /dev/xvdd2: The two block devices that will form the RAID-1 array.

--spare-devices=1 /dev/xvdd3: Specifies one spare device (/dev/xvdd3). A spare device is used to automatically replace a failed device in the RAID array.

Option Analysis:

A.Incorrect because it specifies RAID level 5 (--level=5), which requires at least three devices and does not match the requirement for RAID-1.

B.Incorrect because it does not include the--spare-devices=1option, meaning there is no spare device included in this configuration.

C.Correct as it specifies RAID-1 (--level=1), two active devices (--raid-devices=2), and one spare device (--spare-devices=1).

D.Incorrect because it specifies RAID level 0 (--level=0), which is a striped set (no redundancy), not a mirrored set (RAID-1).

Oracle Linux Reference:For more detailed information aboutmdadmand RAID configurations in Oracle Linux 8, refer to the following Oracle Linux documentation:

Oracle® Linux 8 Managing Storage Devices - RAID Configuration

Oracle® Linux 8 mdadm Manual

These references provide comprehensive details on RAID levels,mdadmcommand syntax, and options for creating and managing RAID arrays in Oracle Linux.

Option D: anacron jobs may run only once a day.

Explanation:

Anacronis designed for systems that are not running continuously (e.g., desktops or laptops that may be powered off at night). It ensures that scheduled tasks are executed at the specified intervals.

Anacron jobs are defined with periods indays. The minimal unit of time for scheduling in Anacron isone day. Therefore, Anacron can schedule jobs to runonce a dayat most.

It is not intended for tasks that need to run multiple times per day.

Oracle Linux Reference:

Oracle® Linux 8: Scheduling Tasks- Section onAnacron Configuration Files:

"Anacron is used to run commands periodically with a frequency specified in days."

Option E: anacron jobs are used to run cron jobs if the system was powered off when they were scheduled to run.

Explanation:

Anacron complements Cron by ensuring thatscheduled jobs are not missedif the system is powered off or in standby mode at the time they were supposed to run.

When the system boots up, Anacron checks for any scheduled jobs that did not run and executes them accordingly.

This is particularly useful for laptops or desktops that are not always on.

Oracle Linux Reference:

Oracle® Linux 8: Scheduling Tasks- Section onUnderstanding Anacron:

"Anacron is designed to run commands periodically with specified frequency, but unlike cron, it does not assume that the system is running continuously."

Why Other Options Are Not Correct:

Option A:cron jobs may run only once a minute.

Explanation:

Cron allows scheduling tasks with a minimum granularity ofone minute. However, this means that tasks can be scheduled to runevery minute, not limited to only once a minute.

Multiple cron jobs can be scheduled to run at the same minute.

Therefore, the statement is misleading; cron jobs can runas frequently as every minute, but notonly once a minute.

Option B:All crontabs are held in the /etc/cron.d directory.

Explanation:

The /etc/cron.d directory is used for system-wide cron jobs provided by packages or administrators.

User-specific cron jobs are stored in /var/spool/cron/ or managed via the crontab command and not placed in /etc/cron.d.

Additionally, the system crontab file is /etc/crontab, and there are also directories like /etc/cron.hourly, /etc/cron.daily, etc.

Option C:The crond daemon looks for jobs only in /etc/crontab.

Explanation:

The crond daemon checks multiple locations for scheduled jobs:

User crontabs managed via the crontab -e command (stored in /var/spool/cron/).

System-wide crontab file (/etc/crontab).

The /etc/cron.d/ directory.

The /etc/cron.hourly/, /etc/cron.daily/, /etc/cron.weekly/, and /etc/cron.monthly/ directories.

Therefore, crond does not look for jobsonlyin /etc/crontab.

Conclusion:

OptionsDandEare correct because they accurately describe the characteristics and purposes of Anacron in the context of scheduling tasks on an Oracle Linux system.

Option A (Correct):A user private group (UPG) ensures that each user has their own unique group created with the same name and ID as the user.

Option E (Correct):The UPG model helps prevent other users from modifying files by default, as newly created files are assigned to the user’s unique group and not to a shared group.

Option B (Incorrect):UPG does not give the capability to create new group users; this is related to group management commands.

Option C (Incorrect):UPG does not providesudocapabilities;sudoconfiguration is managed separately.

Option D (Incorrect):UPGs do not limit reading files to group users by default; it depends on specific file permissions.

Oracle Linux Reference:Refer to:

Oracle® Linux 8: Managing Users and Groups

Explanation of Answer A:Consistent network device naming is enabled by default in Oracle Linux 8. This feature ensures that network interfaces retain their names across reboots, which is important for maintaining network configuration consistency. This is managed through the Predictable Network Interface Names feature, which is part of thesystemdproject and is implemented inudev.

Explanation of Answer B:Theudevdevice manager is responsible for dynamically managing device nodes in the/devdirectory. It generates network interface names based on several naming schemes, such as the interface’s physical location on the bus (likeenp0s3), MAC address, or other attributes. These schemes are used to provide consistent and predictable names for network interfaces.

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.

Explanation of Answer D:The/etc/login.defsfile in Oracle Linux contains configuration settings related to user account policies, including password aging controls. This includes settings such asPASS_MAX_DAYS,PASS_MIN_DAYS, andPASS_WARN_AGE, which define the maximum number of days a password is valid, the minimum number of days between password changes, and the number of days before password expiration to warn users, respectively.

Explanation of Answer E:The/etc/login.defsfile also contains settings for the encryption method used to encrypt user passwords. TheENCRYPT_METHODparameter specifies the hashing algorithm, such as SHA512, that is used to encrypt user passwords stored in/etc/shadow.