702-100 Linux Professional Institute BSD Specialist Questions and Answers

The /etc/nsswitch.conf file defines the order of the name resolution methods used on a NetBSD system. It specifies the sources and their priority for various databases, such as hosts, services, protocols, etc. The sources can be files, DNS, NIS, or other services. For example, the following line in /etc/nsswitch.conf indicates that the hosts database should be looked up first in the /etc/hosts file, then in the DNS server, and finally in the NIS server:

hosts: files dns nis

References :

nsswitch.conf(5) - NetBSD Manual Pages

Chapter 23. The NetBSD Network Configuration Files

Nmap is a program that can be used to enumerate all responsive hosts on a subnet. Nmap stands for Network Mapper, and it is a tool that can perform network discovery, port scanning, service detection, vulnerability assessment, and more. Nmap can send different types of packets to probe the hosts on a subnet and determine which ones are alive and what services they are running. Nmap can also perform OS fingerprinting, which can identify the operating system of the target hosts. Nmap has many options and features that can customize the scan according to the user’s needs and preferences. The other programs are not suitable for enumerating all responsive hosts on a subnet, because:

A. traceroute: This program is used to trace the route of packets from the source host to the destination host. It can show the intermediate hops and the latency of each hop. However, it cannot show all the hosts on a subnet, only the ones that are on the path to the destination.

B. netstat: This program is used to display the status of network connections, routing tables, interface statistics, and more. It can show the local and remote addresses and ports of the active connections, but it cannot show all the hosts on a subnet, only the ones that are connected to the local host.

D. rtso1: This is not a valid program name, but it may be a typo for rtso, which is a program that can perform TCP SYN scanning. However, this program is not as versatile and powerful as nmap, and it can only scan TCP ports, not UDP or other protocols.

E. route: This program is used to manipulate the routing table, which is used to determine the next hop for a packet based on its destination address.  It can show the destination, gateway, interface, and flags of each route, but it cannot show all the hosts on a subnet, only the ones that are reachable via a specific gateway.  References:   6 : https://nmap.org/book/man.html  7 : https://www.freebsd.org/cgi/man.cgi?query=traceroute & sektion=8 : https://www.freebsd.org/cgi/man.cgi?query=netstat & sektion=1 : https://www.freebsd.org/cgi/man.cgi?query=rtso & sektion=1 : https://www.freebsd.org/cgi/man.cgi?query=route & sektion=8

The sysctl command is used to set and get kernel state variables, including the FreeBSD security level. The security level is a variable named kern.securelevel, which can have values from -1 to 3, with higher values indicating more restrictions. The security level can only be increased, not decreased, unless the system is rebooted or in single-user mode.  The security level affects various operations, such as loading kernel modules, changing immutable flags on files, and modifying device nodes 1 2   References:   1 : https://docs.freebsd.org/en/books/handbook/security/#security-basics-securelevels  2 : https://www.freebsd.org/cgi/man.cgi?query=sysctl & sektion=8

The ports collection on FreeBSD is a package management system that allows users to install third-party software from source or binary packages. The ports collection is stored in the /usr/ports/ directory, which contains subdirectories for different categories of software, such as archivers, databases, editors, etc. Each subdirectory contains one or more ports, which are directories that contain the files needed to build and install the software.  The /usr/ports/ directory can be updated with the portsnap command 3 4

Binary packages are pre-compiled versions of the ports that can be installed with the pkg command. Binary packages are downloaded from the FreeBSD package repository, which is hosted at pkg.freebsd.org. The packages are installed in the /usr/local/ directory by default, and the information about the installed packages is stored in the /usr/local/pkg/ directory. The /usr/local/pkg/ directory contains files with the .db extension, which are SQLite databases that store the metadata of the packages.  The pkg command can query and manipulate these databases 5 6   References:   3 : https://docs.freebsd.org/en/books/handbook/ports/  4 : https://www.freebsd.org/ports/  5 : https://docs.freebsd.org/en/books/handbook/pkgng-intro/  6 : https://www.freebsd.org/cgi/man.cgi?query=pkg & sektion=8

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 swapctl command is used to list, add, or delete swap devices on BSD systems. It can also display the total amount of swap space available and used. The swapctl command takes various options to perform different actions, such as -l to list the swap devices, -a to add a swap device, -d to delete a swap device, and -s to show the swap summary. The other options are not valid BSD commands for managing swap devices.  References:

swapctl(8) - OpenBSD manual pages

FreeBSD Handbook - Chapter 19. The FreeBSD Booting Process

FreeBSD Handbook - Chapter 9. Configuring the FreeBSD Kernel

The date command in BSD systems provides the following features:

It outputs the time in a specific format. The date command can display the current date and time in various formats, depending on the options and arguments given. For example, the command  date +%Y-%m-%d  will output the date in the format of year-month-day, such as  2023-04-30 . The command  date +%T  will output the time in the format of hour:minute:second, such as  22:51:42 . The command  date +%A  will output the full name of the weekday, such as  Thursday . The date command supports many formatting characters that can be used to customize the output.  For a full list of formatting characters, see the date(1) manual page 1 .

It sets the clock to a specific time. The date command can also be used to set the system date and time, if the user has the appropriate privileges. For example, the command  date 0430225123  will set the date and time to April 30, 2023, 22:51:42. The command  date -u 0430225123  will set the date and time to the same value, but in UTC (Coordinated Universal Time) instead of the local time zone.  The command  date -n  will set the date and time to the current network time, using the ntpd(8) daemon 1 .

The date command does not provide the following features:

It does not display a calendar. The date command only displays the date and time, not a calendar. To display a calendar, the cal(1) or ncal(1) commands can be used instead. For example, the command  cal 4 2023  will display the calendar for April 2023.  The command  ncal -w 2023  will display the calendar for the whole year 2023, with week numbers 2 3 .

It does not send NTP queries. The date command does not send any network requests or queries to NTP (Network Time Protocol) servers. To synchronize the system clock with NTP servers, the ntpd(8) daemon or the ntpdate(8) utility can be used instead. For example, the command  ntpd -q  will query one or more NTP servers and adjust the system clock accordingly.  The command  ntpdate pool.ntp.org  will set the date and time to the value returned by the NTP server pool.ntp.org 4 5 .

It does not change the system’s timezone. The date command does not change the system’s timezone setting, only the date and time values. To change the system’s timezone, the tzsetup(8) utility or the ln(1) command can be used instead. For example, the command  tzsetup  will run an interactive program that allows the user to select a timezone from a list of regions and cities. The command  ln -sf /usr/share/zoneinfo/Europe/Paris /etc/localtime  will create a symbolic link from the file /etc/localtime to the file /usr/share/zoneinfo/Europe/Paris, which contains the timezone information for Paris, France .  References :

date(1) - FreeBSD

cal(1) - FreeBSD

ncal(1) - FreeBSD

ntpd(8) - FreeBSD

ntpdate(8) - FreeBSD

[tzsetup(8) - FreeBSD]

[ln(1) - FreeBSD]

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”

The command  route add default 192.168.1.1  is used to set the default gateway on a BSD system. This command adds a default route to the routing table, directing traffic to the specified gateway IP address when no other route matches.

References :

FreeBSD Handbook - Routing

OpenBSD Change, Add or Display Default Gateway

The cron job syntax consists of five fields that specify the time and date of execution, followed by the command or script to run. The fields are: minute, hour, day of month, month, and day of week. Each field can have a specific value, a range, a list, a wildcard ( ), or a step value. The wildcard ( ) means any possible value for that field. The option B sets the minute field to 0 and the hour field to *, which means the script will run at the 0th minute of every hour, regardless of the day, month, or weekday. This is equivalent to once per hour. The other options are either invalid syntax or do not match the desired frequency. For example, option A sets all fields to *, which means the script will run every minute of every hour of every day, month, and weekday. Option C sets the minute field to * and the hour field to 0, which means the script will run every minute of the 0th hour, or once per day at midnight. Option D has a typo (o instead of *) and option E sets the day of month field to o, which is not a valid value.  References:

crontab  - FreeBSD crontab(5) Manual Page 1

Crontab Explained in Linux [With Examples]  - Linux Handbook 2

The last command displays a list of the last logged in users on a BSD system. The output consists of several columns that show the user name, the terminal name, the login date and time, and the logout date and time or the current status. The option C is the only line that matches the format of the last command output. It shows that the user root logged in on the terminal ttyv0 on Saturday, May 18, 2023 at 13:35 and is still logged in. The other options are either invalid lines or belong to other commands or sources. For example, option A is the output of the uptime command, option B is a line from the /var/log/auth.log file, option D is a line from the ps command, and option E is the output of the uname -a command.  References:

[last] - FreeBSD last(1) Manual Page

[How to use the last command in Linux] - Linuxize

The command that generates the output showing kernel module IDs, reference counts, addresses, sizes, and names is kldstat in FreeBSD. This command is used to display the status of loaded kernel modules, including those loaded dynamically. The output format shown in the question is characteristic of kldstat , where it lists the kernel modules currently loaded into the system's memory along with their respective details.

References :

FreeBSD Handbook or Manual Pages (man pages), specifically the section on kernel modules and the kldstat command.

Linux Professional Institute BSD Specialist resources, which cover FreeBSD commands and utilities, including those for managing kernel modules.

The setenv command is used to set an environment variable in the csh or tcsh shell. The syntax is setenv VAR VALUE, where VAR is the name of the variable and VALUE is the value to assign to it. The TZ variable is used to specify the timezone for the shell and its subprocesses. To set the timezone to GMT (Greenwich Mean Time), the command is setenv TZ GMT. This will affect the output of commands like date and ls that display time information. The other options are either invalid syntax or belong to other shells, such as bash or sh.  References:

setenv  - Linux setenv command help and examples 1

TZ  - FreeBSD Environment Variables 2

The find command is used to search for files and directories that match certain criteria. The - -type option specifies the type of file to look for, and the d argument means directories. The . argument means the current directory. Therefore, the command find - -type d searches for all directories within the current directory.  The other options are either invalid or do not match the question.  References:   1 : https://www.comptia.org/training/books/a-core-1-220-1101-study-guide, page 301  2 : https://www.howtogeek.com/771399/how-to-use-the-find-command-in-linux/, section “The Linux find Command”

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 upgrades 1 .

References :

FreeBSD Handbook - Packages and Ports