Practice Free 702-100 Linux Professional Institute BSD Specialist Exam Questions Answers With Explanation

The command grep "non [-] disclosure" legalfile matches the lines in the file that contain the pattern non [-] disclosure, where the brackets indicate a character class that matches either a space or a dash. Therefore, the lines that contain non-disclosure or non - disclosure are matched by the command, while the line that contains disclosure only is not matched. The file has two lines that contain non-disclosure, so the correct answer is E. non-disclosure and non-disclosure Only. References:

• grep - IBM
• Character Classes and Bracket Expressions - GNU

This command and option can be used to perform a reverse DNS lookup, which is the process of finding the domain name or hostname associated with an IP address. The dig command is a tool that can query DNS servers for various types of records, such as A, MX, NS, PTR, etc. The -x option tells dig to perform a reverse DNS lookup by sending a PTR query to the DNS server. For example, to perform a reverse DNS lookup for the IP address 8.8.8.8, the following command can be used:

dig -x 8.8.8.8

The output of this command will show the PTR record for 8.8.8.8, which is dns.google. This means that the hostname for 8.8.8.8 is dns.google. Reverse DNS lookups are useful for verifying the identity of a host, checking for mail server configuration, or troubleshooting network problems

The groups command is used to show the current user’s group memberships on BSD systems. The command prints the names of the primary and secondary groups that the user belongs to, separated by spaces. The primary group is the one that is assigned to new files and directories created by the user. The secondary groups are the ones that grant additional permissions or access to the user. For example, the output of groups for a user named alice might look like this:

alice wheel staff

This means that alice’s primary group is alice, and her secondary groups are wheel and staff. The wheel group is typically used for granting administrative privileges, such as using the su or sudo commands. The staff group might be used for granting access to certain resources or directories that are shared by a group of users.

The other options are either invalid commands or do not show the user’s group memberships. For example, group is not a valid command, ident is used to query an ident protocol server, showuser is not a valid command, and who is used to show who is logged on the system.

References:

• groups - FreeBSD groups(1) Manual Page1
• Group Management - FreeBSD Handbook2

The subnet mask 255.255.224.0 corresponds to the hexadecimal netmask 0xffffe000 shown in the output. This subnet mask indicates a subnet with 19 bits for the network portion and 13 bits for the host portion, allowing for a large number of hosts within the subnet.

References:

• BSD Specialist Exam 702 Objectives - Linux Professional Institute
• FreeBSD Handbook - Networking

The command netcat is a versatile networking utility that can be used to read from and write to network connections using TCP or UDP protocols. It is often used for debugging and investigating the network and can be used to connect to a remote TCP service.

References:

• BSD Specialist Exam 702 Objectives - Linux Professional Institute
• FreeBSD Handbook - Networking

The command mkdir (short for make directory) creates a new directory with the specified name. The command takes one or more arguments, which are the names of the directories to be created. If the name contains spaces or other special characters, it should be enclosed in quotes. For example, mkdir “My Documents” creates a directory named My Documents. The command also accepts some options, such as -p, which creates the parent directories if they do not exist, or -m, which sets the permissions of the new directory. For example, mkdir -p -m 755 /usr/local/bin creates the directory /usr/local/bin and its parent directories /usr and /usr/local, and sets the permissions of /usr/local/bin to 755 (read, write and execute for the owner, read and execute for the group and others). References:

• [mkdir(1) - FreeBSD Manual Pages]
• [How to Create a Directory in Linux - Linuxize]

The zfs snapshot command creates a snapshot of a ZFS dataset, which is a point-in-time copy of the data. The snapshot name is specified as follows: filesystem@snapname or volume@snapname. The snapshot name must satisfy the naming requirements in ZFS Component Naming Requirements1. In this case, the command zfs snapshot space/data@snap1 creates a snapshot of the dataset space/data named snap1. The other options are either invalid or do not create a snapshot. References: 1:https://docs.oracle.com/cd/E19253-01/819-5461/gbcya/index.html

The nice command is used to run a command with a modified scheduling priority, which affects how much CPU time the command receives. The priority can be specified by the -n option, which takes an integer value between -20 and 19, where lower values indicate higher priority. By default, the nice value is incremented by 10, which means the command runs with lower priority than normal. Only the superuser can specify a negative increment, which means the command runs with higher priority than normal. For example, the command nice -n 5 date runs the date command with a priority of 5, while the command nice -n -10 ls runs the ls command with a priority of -10, but only if the user is the superuser. The nice command is useful for running CPU-intensive commands that do not need to finish quickly, or for running commands that need more CPU time than normal. References:

• nice - FreeBSD, the manual page for the nice command on FreeBSD.
• HowTo: Use ps, kill, nice, and killall To Manage processes in FreeBSD and OS X Unix Operating System - nixCraft, a tutorial on how to use the nice command and other process management commands on FreeBSD and OS X.

This line stems from an ARP table because it shows the association between an IP address (192.168.122.1) and a MAC address (52:54:00: a3:4e: 0e) on a network interface (em0). ARP stands for Address Resolution Protocol, which is used to map IP addresses to MAC addresses on a local network. An ARP table is a list of these mappings that is maintained by each host on the network. The other lines are not from an ARP table, but from different sources, such as:

• B. inet 192.168.122.11 netmask 0xffffff00 broadcast 192.168.122.255: This line is from the output of the ifconfig command, which displays the configuration of network interfaces. It shows the IP address, netmask, and broadcast address of the interface.
• C. 127.0.0.1 localhost localhost.my.domain: This line is from the /etc/hosts file, which is used to map hostnames to IP addresses. It shows that the loopback address (127.0.0.1) is associated with the hostname localhost and the fully qualified domain name localhost.my.domain.
• D. tcp4 0 0 192.168.122.11.22 192.168.122.1.38058 ESTABLISHED: This line is from the output of the netstat command, which displays the status of network connections. It shows that there is an established TCP connection between the local host (192.168.122.11) on port 22 and the remote host (192.168.122.1) on port 38058.
• E. localhost link#2 UH lo0: This line is from the output of the route command, which displays the routing table. It shows that the destination localhost is reachable via the link layer interface lo0, which is the loopback interface. The UH flags indicate that the route is up and uses a host-specific gateway. References: 1: https://docs.freebsd.org/en/books/handbook/network-arp/ 2: https://www.freebsd.org/cgi/man.cgi?query=ifconfig&sektion=8 3: https://www.freebsd.org/cgi/man.cgi?query=hosts&sektion=5 4: https://www.freebsd.org/cgi/man.cgi?query=netstat&sektion=1 5: https://www.freebsd.org/cgi/man.cgi?query=route&sektion=8

The cat command is used to concatenate and display files. The mail command is used to send and receive mail messages. The pipe symbol (I) is used to redirect the output of one command to the input of another command. Therefore, the command cat myconfigfile I mail me@mycompany.com sends the contents of the file myconfigfile by email to me@mycompany.com. The cat command reads the file and displays its contents to the standard output, which is then piped to the mail command, which reads the standard input and sends it as a mail message to the specified address. The mail command also prompts the user to enter a subject line and optionally some additional headers for the message. Alternatively, the subject line can be specified by the -s option of the mail command. For example, the command cat myconfigfile I mail -s "My config file" me@mycompany.com sends the same message with the subject “My config file”. References:

• [cat - FreeBSD], the manual page for the cat command on FreeBSD.
• [mail - FreeBSD], the manual page for the mail command on FreeBSD.
• [How to send email from the Linux command line - LinuxConfig.org], a tutorial on how to use the mail command and other email clients on Linux.

The zpool create command is used to initialize ZFS on one or more block devices and create a storage pool. A storage pool is a collection of devices that provide physical storage and data replication for ZFS datasets. The zpool create command takes the name of the pool and the devices to be added as arguments. For example, zpool create mypool c0t0d0 c0t1d0 c0t2d0 would create a pool named mypool with three devices. The other options are either invalid or do not initialize ZFS. References: 1: https://www.comptia.org/training/books/a-core-1-220-1101-study-guide, page 302  2: https://docs.oracle.com/cd/E19253-01/819-5461/gbchx/index.html, section “Creating a ZFS Storage Pool”

A symbolic link, or symlink, is a special type of file that points to another file or directory on the file system1. When creating a symbolic link with the ln command, the syntax is as follows:

ln -s target link

where target is the file or directory to link to, and link is the name of the symbolic link2. If the link name already exists, the ln command will fail and display an error message indicating that the target already exists3. This is because the ln command does not overwrite existing files or directories by default4. Therefore, the only way to create a symbolic link with the same name as an existing file or directory is to manually remove the existing target first, and then run the ln command again. Alternatively, the ln command can be used with the -f (force) option, which will remove the existing target and create the symbolic link in one step4. However, this option is not mentioned in the question, so the correct answer is A.

References: 1: How to Create Symbolic Links in Linux [Complete Guide] - Linux Handbook 2: Ln Command in Linux (Create Symbolic Links) | Linuxize 3: How to Create and Use Symbolic Links (aka Symlinks) on Linux - How-To Geek 4: Symbolic Links in Unix/Linux - Stack Abuse

The command pkg upgrade is used to update FreeBSD packages to newer versions. It compares the versions of installed packages with those in the repositories and performs upgrades as necessary. The pkg update command is used to update the repository catalog, but it does not perform the actual package upgrades1.

References:

• FreeBSD Handbook - Packages and Ports