Oracle 1z0-106 Oracle Linux 8 Advanced System Administration Exam Practice Test

Explanation of Answer A:Thesysctl -wcommand is used to modify kernel parameters at runtime. It allows you to set the value of a specific parameter in the/proc/sysdirectory. For example,sysctl -w net.ipv4.ip_forward=1will enable IP forwarding by writing the value directly to the corresponding file in/proc/sys.

Explanation of Answer B:Using theechocommand to write values directly to specific files in the/proc/sysdirectory is another method to change kernel parameters dynamically for the running system. For instance,echo 1 > /proc/sys/net/ipv4/ip_forwardachieves the same effect as thesysctl -wcommand.

Explanation of Answer B:The commandssh -L 5011:127.0.0.1:80 bob@10.10.2.20 -f sleep 30creates a local port forward. This means port5011on the client machine is forwarded to port80on the remote machine (10.10.2.20) using the SSH connection.

Explanation of Answer E:The-foption of thesshcommand causes the SSH connection process to fork to the background after authentication is complete. Thesleep 30command keeps the SSH connection alive for 30 seconds.

To use a file as swap space, it must first be initialized with themkswapcommand. Theddcommand creates an empty file, butmkswapformats this file to be used as swap space. This command writes the necessary swap header to the file, making it recognizable by the system as a valid swap area.

Explanation of Answer D:After initializing the swap file withmkswap, you can optionally assign a label to the swap file using theswaplabelcommand. This is not strictly required, but it can be useful for identifying swap files, especially if you are using multiple swap devices.

Option A: Ksplice can be used without a network connection

Explanation:

Ksplice provides anOffline Clientspecifically designed for systems that do not have a direct connection to the internet. This client allows administrators to download Ksplice updates on a system with internet access and then transfer them to the offline system for installation.

This means Ksplice can be effectively used in environments with strict security policies where network connectivity is restricted or not available.

Oracle Linux Reference:

Oracle® Linux 8: Ksplice User's Guide- Section on "Using the Ksplice Offline Client":

"The Ksplice Offline client enables you to apply Ksplice updates to systems that do not have direct access to the Internet or to the Oracle Uptrack server."

Option B: It can patch the kernel without shutting down the system.

Explanation:

The primary purpose of Ksplice is to allow administrators to apply critical security patches to the running kernelwithout requiring a rebootor shutting down the system. This ensures high availability and minimizes downtime, which is crucial for production environments.

Ksplice works by performingjust-in-time (JIT) compilationof kernel patches and applying them directly to the running kernel in memory.

Oracle Linux Reference:

Oracle® Linux 8: Ksplice User's Guide- Introduction:

"Ksplice enables you to keep your systems up to date and secure by applying important kernel security updates without rebooting."

Why Other Options Are Not Correct:

Option C:Yum cannot upgrade a kernel patched by Ksplice

Explanation:

This statement is false. While Ksplice patches the running kernel in memory, yum can still upgrade the kernel packages on disk. After a yum kernel update, a reboot would be necessary to run the new kernel version, but yum operations are not hindered by Ksplice patches.

Oracle Linux Reference:

Oracle® Linux 8: Ksplice User's Guide- Compatibility with Package Managers:

"Ksplice works seamlessly with package management tools like yum and dnf. You can continue to use these tools to manage your kernel packages."

Option D:Ksplice has two clients; each can run in three different modes.

Explanation:

While Ksplice does have two clients (the online and offline clients), the statement about each running in three different modes is inaccurate or misleading. The clients do not operate in "three different modes" per se.

Oracle Linux Reference:

No official documentation supports the claim of "three different modes" for each client.

Option E:The Ksplice client is freely available to all customers.

Explanation:

Ksplice is a feature available to customers with an active Oracle Linux Premier Support subscription. It is not freely available to all users.

Oracle Linux Reference:

Oracle® Linux 8: Ksplice User's Guide- Access Requirements:

"To use Ksplice, your system must be covered by an Oracle Linux Premier Support subscription."

Conclusion:

Options A and B are correct because Ksplice can be used without a network connection via the offline client, and it allows patching the kernel without shutting down the system, ensuring minimal downtime.

Understanding the Command:

$ podman run --name=oracleshell -it oraclelinux:8-slim

(Note: The image is likely oraclelinux:8-slim without a space.)

podman run:Creates and starts a new container.

--name=oracleshell:Assigns the name oracleshell to the container.

-it:Runs the container in interactive mode with a pseudo-TTY.

oraclelinux:8-slim:Specifies the image to use.

Option A: The container creates and starts an interactive shell.

Explanation:

The -it option runs the container interactively.

If no command is specified, it executes the default command in the image (usually /bin/bash).

This provides an interactive shell inside the container.

Oracle Linux Reference:

Oracle® Linux 8: Managing Containers-Running Containers Interactively:

"You can run a container in interactive mode using the -i and -t options together."

Option D: The container is created and started in a single command.

Explanation:

The podman run command handles both creation and starting of the container.

There's no need to create the container separately.

Oracle Linux Reference:

Oracle® Linux 8: Managing Containers-Creating and Running Containers:

"The podman run command creates and starts a container in one operation."

Why Other Options Are Incorrect:

Option B:The container does not need to pre-exist; podman run creates it if it doesn't exist.

Option C:If the image doesn't exist locally, podman will attempt to pull it from the registry.

Oracle Linux Reference:

Oracle® Linux 8: Managing Containers-Pulling Images:

"If you attempt to run a container with an image that does not exist locally, Podman automatically pulls the image from a registry."

Option E:The container is not removed upon exit unless the --rm option is used.

Oracle Linux Reference:

Oracle® Linux 8: Managing Containers-Automatically Removing Containers:

"Use the --rm option to automatically remove the container when it exits."

Conclusion:

Correct Options:A, D

Summary:The command creates and starts a new container named oracleshell and opens an interactive shell session inside it.

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.

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

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.

Option A (Correct):/lib64/securityis a common directory where PAM (Pluggable Authentication Module) libraries are stored for 64-bit systems.

Option D (Correct):/lib/securityis another directory where PAM libraries are stored, usually on 32-bit systems or as a fallback for 64-bit systems.

Option B (Incorrect):/etc/pam.dcontains configuration files for PAM modules but does not store the modules themselves.

Option C (Incorrect):/usr/libis a general directory for libraries but does not specifically store PAM modules.

Option E (Incorrect):/var/libis typically used for variable state information and is not relevant for storing PAM modules.

Oracle Linux Reference:Refer to:

Oracle® Linux 8: Managing Authentication

Understanding DNF Modules:

DNF modules in Oracle Linux 8 provide a way to offer different versions of software (packages) to users, allowing them to choose the version that best suits their needs. Modules help in managing multiple versions of software by grouping packages, defining streams, and using profiles for configurations.

Option A: Modules are a group of packages that are installed together along with dependencies.

Explanation:

Modulesare collections of packages that are grouped together to represent an application, language runtime, or any logical set.

When you install a module, you are installing a set of packages along with their dependencies.

This grouping ensures that all necessary components are installed for the software to function correctly.

Oracle Linux Reference:

Oracle® Linux 8: Managing Software-About Modules:

"A module is a group of packages that represents a component, such as an application, a language runtime, or a set of tools."

Option B: Installing a module allows a user to select a specific stream.

Explanation:

Streamsin a module represent different versions of the software.

When installing a module, you can select a specific stream to install the desired version.

This allows users to choose between multiple versions of the same software provided within the module.

Oracle Linux Reference:

Oracle® Linux 8: Managing Software-About Module Streams:

"Each module can have one or more streams, which represent versions of the module content."

Example Command:

# dnf module list nodejs

This command lists available streams for the nodejs module.

Option F: Packages exist in multiple streams, where each stream contains a different version.

Explanation:

Within a module, each stream can contain different versions of the packages.

This means the same package can exist in multiple streams but with different versions in each stream.

This setup allows users to install the version of the software that meets their requirements.

Oracle Linux Reference:

Oracle® Linux 8: Managing Software-About Module Streams:

"Different streams can contain different versions of the software, allowing you to select the version that best suits your needs."

Why Other Options Are Incorrect:

Option C: Profiles are used to provide alternate versions of the same module.

Explanation:

Profilesdefine sets of packages within a module stream for specific use cases or configurations, not alternate versions.

Streams provide alternate versions, whereas profiles provide different package sets within a stream.

Oracle Linux Reference:

Oracle® Linux 8: Managing Software-About Module Profiles:

"A profile is a list of packages that defines a particular use case for a module stream."

Option D: Streams are used to define optional configurations of modules.

Explanation:

Streams define different versions of software, not optional configurations.

Optional configurations are managed through profiles within a stream.

Oracle Linux Reference:

Profiles handle configurations, while streams handle versions.

Option E: Streams cannot declare dependencies on the streams of other modules.

Explanation:

Streams can declare dependencies on specific streams of other modules.

This allows modules to work together with compatible versions.

Oracle Linux Reference:

Oracle® Linux 8: Managing Software-Module Dependencies:

"Modules can declare dependencies on specific streams of other modules."

Option G: Switching an enabled module stream automatically changes installed packages.

Explanation:

Switching streams does not automatically change installed packages.

You must reset the module and install the new stream's packages manually.

Oracle Linux Reference:

Oracle® Linux 8: Managing Software-Switching Module Streams:

"To switch to a different module stream, you must reset the module and then install the packages from the new stream."

Conclusion:

Correct Options:A, B, F

Summary:Modules group packages with dependencies, installing a module allows selecting a specific stream (version), and packages can exist in multiple streams with different versions.

Option C (Correct):Theall-squashoption in the/etc/exportsfile maps all user and group requests from remote systems to the anonymous user (nfsnobody) on the NFS server. However, because theanonuidandanongidoptions are specified with501, all incoming requests are explicitly mapped to the UID and GID of the unprivileged local user with UID 501 and GID 501. Thero(read-only) option allows all clients to mount/usr/shared/toolsas read-only.

Option A (Incorrect):This is incorrect because all clients can mount the directory, but all users' requests are squashed to UID 501. There is no exception for local 501 users.

Option B (Incorrect):The answer is incorrect because it incorrectly states "privileged local 501 user." The UID 501 is typically an unprivileged user.

Option D (Incorrect):Theall-squashoption does not override the UID and GID explicitly defined byanonuidandanongid. Instead, it maps all remote requests to these values.

Option E (Incorrect):Theanonuidandanongiddirectives are not ignored; they are explicitly used to map all requests to the specified UID and GID.

Oracle Linux Reference:For more information on NFS exports and options, refer to:

Oracle® Linux 8: Managing NFS and NIS

man exportsfor details on export options.

Option A (Correct):A slice unit in systemd is a grouping mechanism used for hierarchical management of resources (such as CPU, memory, and I/O) among a group of processes.

Options B, C, D (Incorrect):These options do not correctly describe the role or characteristics of slice units in Oracle Linux 8.

Oracle Linux Reference:Refer to:

Oracle® Linux 8: Managing Services with systemd

Option A (Correct):Boot parameters are set in/etc/default/grubunder theGRUB_CMDLINE_LINUXdirective. After modifying this file, thegrub2-mkconfigcommand must be run to apply changes.

Option C (Correct):The/boot/loader/entries/directory contains configuration files for each kernel version, which store the boot parameters separately.

Option B (Incorrect):Boot parameters specified at the GRUB command line are not persistent across reboots unless added to the configuration file.

Option D (Incorrect):Parameters set from the GRUB menu are temporary and do not apply to subsequent reboots.

Oracle Linux Reference:Refer to:

Oracle® Linux 8: Configuring GRUB2

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

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.

Explanation of Answer C:Bothatandbatchcan accept commands from standard input or from a file specified using the-foption. This allows scheduling of tasks by providing the commands directly or reading them from a file.

Explanation of Answer E:Theatcommand schedules a one-time task to run at a specified time. It is used to execute commands once at a particular time in the future.

Explanation of Answer A:Oracle Linux 8 uses cgroups version 2 (cgroups v2) by default. cgroups v2 is a unified hierarchy system that introduces improvements over version 1, including a simplified interface and better resource management capabilities.

Explanation of Answer B:A control group (cgroup) is a mechanism for grouping processes and setting limits or parameters on their resource usage, such as CPU, memory, or I/O. These limits and parameters are configured and managed through the cgroups filesystem.

Option C (Correct):Thedmesg -Tcommand converts the timestamps in the kernel ring buffer messages to a human-readable format. The defaultdmesgoutput shows the timestamps in a raw format (seconds since the kernel started), while the-Toption translates these timestamps into a human-readable date and time.

Option A (Incorrect):The-toption is used to remove the timestamps entirely from the output.

Option B (Incorrect):The-xoption provides extended information about the message (e.g., facility, level).

Option D (Incorrect):The-Woption waits for new messages and does not convert timestamps to a human-readable format.

Oracle Linux Reference:Refer to:

man dmesgfor more details ondmesgoptions.