Practice Free 102-500 Exam Online Questions
Question #1
What is true about the Hop Limit field in the IPv6 header?
- A . The field is not changed during the transport of a package.
- B . The field is transmitted within a hop-by-hop extension header.
- C . Each router forwarding the packet increases the field’s value.
- D . Each router forwarding the packet decreases the field’s value.
- E . For multicast packages, the field’s value is always 1.
Correct Answer: D
D
Explanation:
The Hop Limit field in the IPv6 header is similar to the Time to Live (TTL) field in the IPv4 header. It specifies the maximum number of hops (routers) that a packet can traverse before reaching its destination. Each router that receives the packet decrements the Hop Limit field by one and forwards the packet. If the Hop Limit field reaches zero, the packet is discarded and an ICMPv6 error message is sent back to the source. This mechanism prevents packets from looping indefinitely in the network12
Reference: 1: IPv6 packet – Wikipedia 2: IP Time to Live (TTL) and Hop Limit Basics – Packet Pushers
D
Explanation:
The Hop Limit field in the IPv6 header is similar to the Time to Live (TTL) field in the IPv4 header. It specifies the maximum number of hops (routers) that a packet can traverse before reaching its destination. Each router that receives the packet decrements the Hop Limit field by one and forwards the packet. If the Hop Limit field reaches zero, the packet is discarded and an ICMPv6 error message is sent back to the source. This mechanism prevents packets from looping indefinitely in the network12
Reference: 1: IPv6 packet – Wikipedia 2: IP Time to Live (TTL) and Hop Limit Basics – Packet Pushers
Question #2
What output will the command seq 10 produce?
- A . A continuous stream of numbers increasing in increments of 10 until stopped.
- B . The numbers 1 through 10 with one number per line.
- C . The numbers 0 through 9 with one number per line.
- D . The number 10 to standard output.
Correct Answer: B
B
Explanation:
The seq command in Linux is used to print a sequence of numbers, which can be piped to other commands or used in for loops and bash scripts1. The command can generate a list of integers or real numbers, with options to control the start, end, and increment of the sequence. The general syntax of the command is seq [options] specification1.
If you launch seq with a single number as a command-line parameter, it counts from one to that number. It then prints the numbers in the terminal window, one number per line2. For example, seq 10 will produce the following output:
1
2
3
4
5
6
7
8
9
10
Therefore, the correct answer is
B. The numbers 1 through 10 with one number per line.
Reference: 1: 10+ Seq Commands with Examples in Linux C LinuxWizardry 2: How to Use the seq Command on Linux – How-To Geek
B
Explanation:
The seq command in Linux is used to print a sequence of numbers, which can be piped to other commands or used in for loops and bash scripts1. The command can generate a list of integers or real numbers, with options to control the start, end, and increment of the sequence. The general syntax of the command is seq [options] specification1.
If you launch seq with a single number as a command-line parameter, it counts from one to that number. It then prints the numbers in the terminal window, one number per line2. For example, seq 10 will produce the following output:
1
2
3
4
5
6
7
8
9
10
Therefore, the correct answer is
B. The numbers 1 through 10 with one number per line.
Reference: 1: 10+ Seq Commands with Examples in Linux C LinuxWizardry 2: How to Use the seq Command on Linux – How-To Geek
Question #3
What is true regarding the command userdel –force –remove bob? (Choose TWO correct answers.)
- A . The user bob is removed from the system’s user database.
- B . The user bob’s home directory is removed.
- C . The locate database is updated to drop files owned by bob.
- D . All files owned by bob are remove from all mounted filesystems.
- E . In case bob was the last member of a group, that group is deleted.
Correct Answer: A, B
A, B
Explanation:
The command userdel –force –remove bob is used to delete the user account named bob and all its associated files. The –force option forces the removal of the user account, even if the user is still logged in. The –remove option forces userdel to remove the user’s home directory and mail spool, even if another user uses the same home directory or if the mail spool is not owned by the specified user12. Therefore, options A and B are true regarding this command. The other options are not true because:
Option C is false because the locate database is not updated by the userdel command. The locate database is updated by the updatedb command, which is usually run by cron as a scheduled job3. Option D is false because the userdel command does not remove all files owned by bob from all mounted filesystems. The userdel command only removes the user’s home directory and mail spool, and it does not search for and delete the user files located in other file systems. You have to search for and delete the files manually1.
Option E is false because the userdel command does not delete the group with the same name as the user, unless the USERGROUPS_ENAB parameter is set to yes in the /etc/login.defs file and the group has no other members14.
Reference: How to Delete/Remove Users in Linux (userdel Command) | Linuxize
userdel(8) ― Linux manual page
updatedb(8) ― Linux manual page
Understanding the /etc/login.defs File | Linuxize
A, B
Explanation:
The command userdel –force –remove bob is used to delete the user account named bob and all its associated files. The –force option forces the removal of the user account, even if the user is still logged in. The –remove option forces userdel to remove the user’s home directory and mail spool, even if another user uses the same home directory or if the mail spool is not owned by the specified user12. Therefore, options A and B are true regarding this command. The other options are not true because:
Option C is false because the locate database is not updated by the userdel command. The locate database is updated by the updatedb command, which is usually run by cron as a scheduled job3. Option D is false because the userdel command does not remove all files owned by bob from all mounted filesystems. The userdel command only removes the user’s home directory and mail spool, and it does not search for and delete the user files located in other file systems. You have to search for and delete the files manually1.
Option E is false because the userdel command does not delete the group with the same name as the user, unless the USERGROUPS_ENAB parameter is set to yes in the /etc/login.defs file and the group has no other members14.
Reference: How to Delete/Remove Users in Linux (userdel Command) | Linuxize
userdel(8) ― Linux manual page
updatedb(8) ― Linux manual page
Understanding the /etc/login.defs File | Linuxize
Question #4
Which of the following tasks can be accomplished using the command date? (Choose TWO correct answers.)
- A . Synchronize the hardware and system clocks.
- B . Output date and time in different formats.
- C . Set the system clock.
- D . Set the hardware clock.
- E . Update the time via NTP.
Correct Answer: B
B
Explanation:
The date command is used to display and set the system date and time. It can also be used to print the time in different formats and calculate future and past dates. The date command has the following syntax:
date [option]… [+format]
The format controls begin with the % symbol and are substituted by their current values. For example, to display the current year, month, and day, we can use the following command: date +"Year: %Y, Month: %m, Day: %d"
To set the system clock manually, we can use the –set or -s option followed by the date and time string. For example, to set the date and time to 5:30 PM, May 13, 2010, we can use the following command:
date –set="20100513 05:30"
The other tasks are not possible with the date command because:
Synchronize the hardware and system clocks: The date command cannot synchronize the hardware and system clocks. To do this, we need to use the hwclock command, which can read or set the hardware clock, and also synchronize it with the system clock.
Set the hardware clock: The date command cannot set the hardware clock. To do this, we need to use the hwclock command with the –systohc or -w option, which will copy the system time to the hardware clock.
Update the time via NTP: The date command cannot update the time via NTP (Network Time
Protocol). To do this, we need to use the ntpdate command, which will query an NTP server and set
the system clock accordingly.
Reference: Date Command in Linux: How to Set, Change, Format and Display Date date command in Linux with examples – GeeksforGeeks Date Command in Linux | Linuxize
B
Explanation:
The date command is used to display and set the system date and time. It can also be used to print the time in different formats and calculate future and past dates. The date command has the following syntax:
date [option]… [+format]
The format controls begin with the % symbol and are substituted by their current values. For example, to display the current year, month, and day, we can use the following command: date +"Year: %Y, Month: %m, Day: %d"
To set the system clock manually, we can use the –set or -s option followed by the date and time string. For example, to set the date and time to 5:30 PM, May 13, 2010, we can use the following command:
date –set="20100513 05:30"
The other tasks are not possible with the date command because:
Synchronize the hardware and system clocks: The date command cannot synchronize the hardware and system clocks. To do this, we need to use the hwclock command, which can read or set the hardware clock, and also synchronize it with the system clock.
Set the hardware clock: The date command cannot set the hardware clock. To do this, we need to use the hwclock command with the –systohc or -w option, which will copy the system time to the hardware clock.
Update the time via NTP: The date command cannot update the time via NTP (Network Time
Protocol). To do this, we need to use the ntpdate command, which will query an NTP server and set
the system clock accordingly.
Reference: Date Command in Linux: How to Set, Change, Format and Display Date date command in Linux with examples – GeeksforGeeks Date Command in Linux | Linuxize
Question #5
Which of the following commands is used to rotate, compress, and mail system logs?
- A . rotatelog
- B . striplog
- C . syslogd –rotate
- D . logrotate
- E . logger
Correct Answer: D
D
Explanation:
The logrotate command is a tool for rotating, compressing, and mailing system logs. It is designed to ease the administration of systems that generate large numbers of log files. It allows automatic rotation, compression, removal, and mailing of log files. Each log file may be handled daily, weekly, monthly, or when it grows too large. Normally, logrotate is run as a daily cron job1. The logrotate command reads the configuration files specified on the command line or in the /etc/logrotate.conf and /etc/logrotate.d directories. These configuration files can set global options and specify log files to rotate and how to handle them. For example, the compress option enables compression of old log files, the mail option sends the log files to a specified email address before being rotated, and the rotate option sets the number of log files to keep12. The logrotate command is part of the LPI’s multi-level Linux professional certification program, and it is covered in the topic 106.1 System logging of the exam 102 objectives3.
Reference: 1: logrotate(8) – Linux man page 2: logrotate command in Linux with examples – Linux command line tutorial 3: Exam 102 Objectives
D
Explanation:
The logrotate command is a tool for rotating, compressing, and mailing system logs. It is designed to ease the administration of systems that generate large numbers of log files. It allows automatic rotation, compression, removal, and mailing of log files. Each log file may be handled daily, weekly, monthly, or when it grows too large. Normally, logrotate is run as a daily cron job1. The logrotate command reads the configuration files specified on the command line or in the /etc/logrotate.conf and /etc/logrotate.d directories. These configuration files can set global options and specify log files to rotate and how to handle them. For example, the compress option enables compression of old log files, the mail option sends the log files to a specified email address before being rotated, and the rotate option sets the number of log files to keep12. The logrotate command is part of the LPI’s multi-level Linux professional certification program, and it is covered in the topic 106.1 System logging of the exam 102 objectives3.
Reference: 1: logrotate(8) – Linux man page 2: logrotate command in Linux with examples – Linux command line tutorial 3: Exam 102 Objectives
Question #6
Which of the following commands can identify the PID od a process which opened a TCP port?
- A . ptrace
- B . strace
- C . debug
- D . lsof
- E . nessus
Correct Answer: D
D
Explanation:
The lsof command, meaning list open files, is a command-line utility in the Linux system to display information about files that are opened by processes1. The lsof command can take various options and arguments to filter and format the output. One of the options that can be used to identify the PID of a process which opened a TCP port is the -i option, which selects the listing of files whose Internet address matches the specified address. The address can be specified as a port number, a host name, or a combination of both. For example, to list the processes that are listening on TCP port 80, one can run:
lsof -i TCP:80
The output shows the command name, the PID, the user name, the file descriptor, the type, the device, the size/off, the node, and the name for each process. The name column shows the local and remote addresses and port numbers for the TCP connection. For example, the output may look like: COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME httpd 1234 root 4u IPv4 12345 0t0 TCP *:80 (LISTEN) httpd 2345 www-data 4u IPv4 12345 0t0 TCP *:80 (LISTEN) httpd 3456 www-data 4u IPv4 23456 0t0 TCP 192.168.1.10:80->192.168.1.20:1234 (ESTABLISHED)
This shows that the httpd command, which is the Apache web server, is listening on TCP port 80 with
the PID 1234 and 2345, and has an established connection with the remote address 192.168.1.20 and
port 1234 with the PID 3456. To kill the process by PID, one can use the kill command with the –
SIGTERM option, which sends a termination signal to the process. For example, to kill the process
with the PID 3456, one can run:
kill -SIGTERM 3456
The other options are not correct because:
ptrace: This is not a command, but a system call that allows a process to trace and control the execution of another process. It is used by debuggers and other tools that need to monitor and manipulate the behavior of other processes2. It does not display the PID of a process which opened a TCP port.
strace: This is a command that traces the system calls and signals of a process. It can be used to diagnose, debug, and monitor the interaction between a process and the kernel3. It does not display the PID of a process which opened a TCP port.
debug: This is not a command, but a general term that refers to the process of finding and fixing errors in a program or system. There are various tools and methods that can be used for debugging, such as debuggers, loggers, profilers, etc4. It does not display the PID of a process which opened a TCP port.
nessus: This is a command that runs the Nessus vulnerability scanner, which is a tool that scans a network or a system for security flaws and potential attacks5. It does not display the PID of a process which opened a TCP port.
Reference: https://www.howtogeek.com/28609/how-can-i-tell-what-is-listening-on-a-tcpip-port-in-windows/
https://bing.com/search?q=identify+PID+of+process+that+opened+a+TCP+port
D
Explanation:
The lsof command, meaning list open files, is a command-line utility in the Linux system to display information about files that are opened by processes1. The lsof command can take various options and arguments to filter and format the output. One of the options that can be used to identify the PID of a process which opened a TCP port is the -i option, which selects the listing of files whose Internet address matches the specified address. The address can be specified as a port number, a host name, or a combination of both. For example, to list the processes that are listening on TCP port 80, one can run:
lsof -i TCP:80
The output shows the command name, the PID, the user name, the file descriptor, the type, the device, the size/off, the node, and the name for each process. The name column shows the local and remote addresses and port numbers for the TCP connection. For example, the output may look like: COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME httpd 1234 root 4u IPv4 12345 0t0 TCP *:80 (LISTEN) httpd 2345 www-data 4u IPv4 12345 0t0 TCP *:80 (LISTEN) httpd 3456 www-data 4u IPv4 23456 0t0 TCP 192.168.1.10:80->192.168.1.20:1234 (ESTABLISHED)
This shows that the httpd command, which is the Apache web server, is listening on TCP port 80 with
the PID 1234 and 2345, and has an established connection with the remote address 192.168.1.20 and
port 1234 with the PID 3456. To kill the process by PID, one can use the kill command with the –
SIGTERM option, which sends a termination signal to the process. For example, to kill the process
with the PID 3456, one can run:
kill -SIGTERM 3456
The other options are not correct because:
ptrace: This is not a command, but a system call that allows a process to trace and control the execution of another process. It is used by debuggers and other tools that need to monitor and manipulate the behavior of other processes2. It does not display the PID of a process which opened a TCP port.
strace: This is a command that traces the system calls and signals of a process. It can be used to diagnose, debug, and monitor the interaction between a process and the kernel3. It does not display the PID of a process which opened a TCP port.
debug: This is not a command, but a general term that refers to the process of finding and fixing errors in a program or system. There are various tools and methods that can be used for debugging, such as debuggers, loggers, profilers, etc4. It does not display the PID of a process which opened a TCP port.
nessus: This is a command that runs the Nessus vulnerability scanner, which is a tool that scans a network or a system for security flaws and potential attacks5. It does not display the PID of a process which opened a TCP port.
Reference: https://www.howtogeek.com/28609/how-can-i-tell-what-is-listening-on-a-tcpip-port-in-windows/
https://bing.com/search?q=identify+PID+of+process+that+opened+a+TCP+port
Question #7
What information related to a user account is modified using the change command?
- A . Default ownership for new files
- B . Group membership
- C . Set of commands available to the user
- D . Password expiry information
- E . Default permissions for new files
Correct Answer: D
Question #7
What information related to a user account is modified using the change command?
- A . Default ownership for new files
- B . Group membership
- C . Set of commands available to the user
- D . Password expiry information
- E . Default permissions for new files
Correct Answer: D
Question #9
Given the following excerpt of the sudo configuration:
jane ANY=NOPASSWD: /bin/kill, /bin/id, PASSWD: /sbin/fdisk
Which of the following statements are true? (Choose three.)
- A . Jane can run /bin/id only after specifying her password.
- B . Jane can run /sbin/fdisk after specifying root’s password.
- C . Jane can run /sbin/fdisk after specifying her password.
- D . Jane can run /bin/kill without specifying a password.
- E . Jane can run /bin/id without specifying her password.
Correct Answer: C, D, E
C, D, E
Explanation:
The sudo configuration file (/etc/sudoers) defines the rules for granting privileges to users or groups to execute commands as another user, usually the superuser or root.
The format of the sudo configuration file is as follows:
user_list host_list=effective_user_list tag_list command_list
The user_list specifies the users who can run the commands, the host_list specifies the hosts where the commands can be run, the effective_user_list specifies the user as whom the commands can be run, the tag_list specifies some options for the commands, and the command_list specifies the commands that can be run.
In this case, the user_list is jane, the host_list is ANY (meaning any host), the effective_user_list is not specified (meaning root by default), the tag_list is NOPASSWD or PASSWD (meaning whether a password is required or not), and the command_list is /bin/kill, /bin/id, or /sbin/fdisk.
Therefore, the sudo configuration file allows jane to run /bin/kill, /bin/id, or /sbin/fdisk as root on any host, but with different password requirements. Specifically:
Jane can run /bin/kill without specifying a password, because the tag_list is NOPASSWD for this command. This means that jane can execute sudo /bin/kill and the command will run as root without asking for any password. This makes option D true.
Jane can run /bin/id without specifying a password, because the tag_list is also NOPASSWD for this command. This means that jane can execute sudo /bin/id and the command will run as root without asking for any password. This makes option E true.
Jane can run /sbin/fdisk after specifying her password, because the tag_list is PASSWD for this command. This means that jane can execute sudo /sbin/fdisk and the command will ask for jane’s password before running as root. This makes option C true. The other options are false because:
Jane cannot run /bin/id only after specifying her password, because the tag_list is NOPASSWD for this command. This makes option A false.
Jane cannot run /sbin/fdisk after specifying root’s password, because the password that is required is jane’s password, not root’s password. This makes option B false.
Reference: LPI Linux Essentials: 1.4. Using sudo
LPI Linux Administrator: 102.5. Use Debian package management LPI Linux Engineer: 201.1. Measure and Troubleshoot Resource Usage LPI Linux Professional Certification Program
C, D, E
Explanation:
The sudo configuration file (/etc/sudoers) defines the rules for granting privileges to users or groups to execute commands as another user, usually the superuser or root.
The format of the sudo configuration file is as follows:
user_list host_list=effective_user_list tag_list command_list
The user_list specifies the users who can run the commands, the host_list specifies the hosts where the commands can be run, the effective_user_list specifies the user as whom the commands can be run, the tag_list specifies some options for the commands, and the command_list specifies the commands that can be run.
In this case, the user_list is jane, the host_list is ANY (meaning any host), the effective_user_list is not specified (meaning root by default), the tag_list is NOPASSWD or PASSWD (meaning whether a password is required or not), and the command_list is /bin/kill, /bin/id, or /sbin/fdisk.
Therefore, the sudo configuration file allows jane to run /bin/kill, /bin/id, or /sbin/fdisk as root on any host, but with different password requirements. Specifically:
Jane can run /bin/kill without specifying a password, because the tag_list is NOPASSWD for this command. This means that jane can execute sudo /bin/kill and the command will run as root without asking for any password. This makes option D true.
Jane can run /bin/id without specifying a password, because the tag_list is also NOPASSWD for this command. This means that jane can execute sudo /bin/id and the command will run as root without asking for any password. This makes option E true.
Jane can run /sbin/fdisk after specifying her password, because the tag_list is PASSWD for this command. This means that jane can execute sudo /sbin/fdisk and the command will ask for jane’s password before running as root. This makes option C true. The other options are false because:
Jane cannot run /bin/id only after specifying her password, because the tag_list is NOPASSWD for this command. This makes option A false.
Jane cannot run /sbin/fdisk after specifying root’s password, because the password that is required is jane’s password, not root’s password. This makes option B false.
Reference: LPI Linux Essentials: 1.4. Using sudo
LPI Linux Administrator: 102.5. Use Debian package management LPI Linux Engineer: 201.1. Measure and Troubleshoot Resource Usage LPI Linux Professional Certification Program
Question #10
Which of the following commands connects to the remote host example.com which has OpenSSH listening on TCP port 2222? (Choose TWO correct answers.)
- A . ssh –port 2222 example.com
- B . ssh -p 2222 example.com
- C . ssh -o Port=2222 example.com
- D . ssh -o GatewayPort=2222 example.com
- E . ssh example.com:2222
Correct Answer: B, C
B, C
Explanation:
T The ssh command is used to connect to a remote host using the Secure Shell (SSH) protocol, which provides encrypted and authenticated communication. The ssh command has the following syntax: ssh [options] [user@]hostname [command]
The options can modify the behavior of the ssh command, such as specifying the port number, the identity file, the cipher, the compression, and the timeout. The user@hostname specifies the username and the hostname of the remote host to connect to. The command is an optional argument that specifies the command to execute on the remote host.
To connect to the remote host example.com which has OpenSSH listening on TCP port 2222, two possible options are:
B. ssh -p 2222 example.com: This option uses the -p flag to specify the port number of the remote host. The -p flag is a shortcut for the Port option, which can also be used with the -o flag.
C. ssh -o Port=2222 example.com: This option uses the -o flag to specify a configuration option for the ssh command. The -o flag can be followed by any option that is valid in the ssh_config file, such as Port, IdentityFile, Cipher, Compression, and ConnectTimeout. The Port option sets the port number of the remote host.
The other options in the question are not correct for this task. The –port option is not a valid option
for the ssh command. The GatewayPort option is used to specify whether remote hosts are allowed to connect to local forwarded ports. The example.com:2222 syntax is not valid for the ssh command.
Reference: LPI 102-500 Exam Objectives, Topic 110.1: Perform security administration tasks
LPI 102-500 Study Guide, Chapter 10: Securing Your System, Section 10.1: Configuring SSH ssh man page
B, C
Explanation:
T The ssh command is used to connect to a remote host using the Secure Shell (SSH) protocol, which provides encrypted and authenticated communication. The ssh command has the following syntax: ssh [options] [user@]hostname [command]
The options can modify the behavior of the ssh command, such as specifying the port number, the identity file, the cipher, the compression, and the timeout. The user@hostname specifies the username and the hostname of the remote host to connect to. The command is an optional argument that specifies the command to execute on the remote host.
To connect to the remote host example.com which has OpenSSH listening on TCP port 2222, two possible options are:
B. ssh -p 2222 example.com: This option uses the -p flag to specify the port number of the remote host. The -p flag is a shortcut for the Port option, which can also be used with the -o flag.
C. ssh -o Port=2222 example.com: This option uses the -o flag to specify a configuration option for the ssh command. The -o flag can be followed by any option that is valid in the ssh_config file, such as Port, IdentityFile, Cipher, Compression, and ConnectTimeout. The Port option sets the port number of the remote host.
The other options in the question are not correct for this task. The –port option is not a valid option
for the ssh command. The GatewayPort option is used to specify whether remote hosts are allowed to connect to local forwarded ports. The example.com:2222 syntax is not valid for the ssh command.
Reference: LPI 102-500 Exam Objectives, Topic 110.1: Perform security administration tasks
LPI 102-500 Study Guide, Chapter 10: Securing Your System, Section 10.1: Configuring SSH ssh man page