102-500 Exam Dumps - LPIC Level 1 Questions and Answers

The statement hosts: files dns is valid in the file /etc/nsswitch.conf. It means that the system will use the local /etc/hosts file and the Domain Name System (DNS) to resolve host names to IP addresses. The order of the sources on the line determines the order in which they will be queried. In this case, the system will first check the /etc/hosts file for a matching host name, and if not found, it will query the DNS servers configured in /etc/resolv.conf. The other statements in the question are not valid in the /etc/nsswitch.conf file. The statement multi on is not a valid keyword or source for any database. The statement 192.168.168.4 dns-server is not a valid syntax for specifying a source or an action. The statement include /etc/nsswitch.d/ is not a valid way to include another file or directory in the /etc/nsswitch.conf file. References:

[LPI Linux Administrator - Exam 102 Objectives - Topic 109: Networking Fundamentals]

nsswitch.conf(5) - Linux manual page

What is the /etc/nsswitch.conf file in Linux – TecAdmin

The keyword files must be listed in the hosts option of the Name Service Switch configuration file in order to make host lookups consult the /etc/hosts file. The files service specifies that the local files, such as /etc/hosts, should be used as a source of information. The order of the services on the line determines the order in which those services will be queried, in turn, until a result is found. For example, if the hosts option is set to:

hosts: files dns

then the /etc/hosts file will be searched first, and if no match is found, the DNS server will be queried next. If the hosts option is set to:

hosts: dns files

then the DNS server will be queried first, and if no match is found, the /etc/hosts file will be searched next. References:

LPI 102-500 Exam Objectives, Topic 110: Network Fundamentals, Weight: 4, 110.3 Basic network troubleshooting

LPI 102-500 Study Guide, Chapter 10: Network Fundamentals, Section 10.3: Basic Network Troubleshooting, Page 125-126

nsswitch.conf: Name Service Switch configuration file

 The keywords dns and files can be used in the /etc/nsswitch.conf file to specify a source for host name lookups. The keyword dns means that the system will use the Domain Name System (DNS) to resolve host names to IP addresses. The keyword files means that the system will use the local /etc/hosts file to resolve host names to IP addresses. The order of the keywords on the line determines the order in which the sources will be queried. For example, the following line in /etc/nsswitch.conf:

hosts: files dns

means that the system will first check the /etc/hosts file for a matching host name, and if not found, it will query the DNS servers configured in /etc/resolv.conf. The other keywords in the question are not valid for the hosts database. The keyword resolv is used for the services database, which contains network service names and port numbers. The keyword remote is not a standard keyword, but it may be used by some applications to implement their own name service providers. The keyword hosts is the name of the database itself, not a source for it. References:

[LPI Linux Administrator - Exam 102 Objectives - Topic 109: Networking Fundamentals]

nsswitch.conf(5) - Linux manual page

What is the /etc/nsswitch.conf file in Linux – TecAdmin

The parameter that must be passed to ifconfig to activate a previously inactive network interface is up. The up parameter tells the kernel to activate the network interface and allow it to send and receive packets. The opposite of up is down, which deactivates the network interface. The up parameter is part of the topic 109.2: Basic network configuration, which is one of the objectives of the LPI Linux Administrator - 102 exam12. References: 1: https://learning.lpi.org/en/learning-materials/102-500/  2: https://www.lpi.org/our-certifications/exam-102-objectives/

The traceroute program can be used to determine the routing path to a given destination by sending packets with incrementing TTL values and recording the source of the ICMP time exceeded messages. This way, it can show the intermediate hops and the round-trip times for each packet. The other programs have different purposes: dig is used to query DNS servers, netstat is used to display network connections and statistics, ping is used to test the reachability of a host by sending ICMP echo requests and measuring the response time, and route is used to manipulate the routing table. References:

LPI 102-500 Exam Objectives, Topic 110: Network Fundamentals, Weight: 4, 110.3 Basic network troubleshooting

LPI 102-500 Study Guide, Chapter 10: Network Fundamentals, Section 10.3: Basic Network Troubleshooting, Page 125-126

 The valid lines in the file /etc/hosts are A and C. The format of the /etc/hosts file is as follows12:

IP_address canonical_hostname [aliases...]

where IP_address is the IPv4 or IPv6 address of the host, canonical_hostname is the official name of the host, and aliases are optional alternative names for the host. Each field is separated by whitespace (spaces or tabs). The # character indicates the beginning of a comment, and the rest of the line is ignored.

The lines B, D, and E are invalid because they do not follow the format of the /etc/hosts file. Line B has the hostname and aliases before the IP address, which is incorrect. Line D has multiple IP addresses and hostnames separated by commas, which is also incorrect. Line E has two IP addresses for the same host, which is not supported by the /etc/hosts file. If a host has more than one IP address, it should have a separate line for each address3.

References:

1: hosts(5) - Linux manual page - man7.org

2: Format of /etc/hosts on Linux (different from Windows?)

3: hosts File Format for TCP/IP - IBM

Port 23 is the well known port for the telnet service, which is a remote connection tool similar to SSH, but without the security of SSH. It uses a client/server model - a telnet client connects to a telnet server using TCP port 23. Due to lack of security, usage of telnet is discouraged in most situations, and firewalls routinely block port 23 to prevent incoming telnet connections. Port 23 is part of the topic 109.1: Fundamentals of internet protocols, which is one of the objectives of the LPI Linux Administrator - 102 exam12. References: 1: https://learning.lpi.org/en/learning-materials/102-500/  2: https://www.lpi.org/our-certifications/exam-102-objectives/

To find the number of IP-addresses that can be used for unique hosts inside an IPv4 subnet, we need to calculate the number of bits that are used for the host part of the IP address. The host part is the part that is not used for the network prefix, which is indicated by the slash notation (/) followed by a number. The number after the slash represents the number of bits that are used for the network prefix, out of the total 32 bits of an IPv4 address. The remaining bits are used for the host part. For example, in the subnet 192.168.2.128/28, the number 28 means that the first 28 bits are used for the network prefix, and the last 4 bits are used for the host part.

The number of IP-addresses that can be used for unique hosts is equal to 2^n - 2, where n is the number of bits in the host part. The -2 is because the first and the last IP addresses in a subnet are reserved for the network address and the broadcast address, respectively, and cannot be assigned to hosts. Therefore, in the subnet 192.168.2.128/28, the number of IP-addresses that can be used for unique hosts is 2^4 - 2, which is 14.

References:

IPv4 - Subnetting - Online Tutorials Library

IP Subnet Calculator

The command that can be used to show the current color depth of the X Server is xwininfo. xwininfo is a command-line tool that provides information about X windows. When executed, it opens a small window and waits for the user to select a window by clicking on it. Then, it displays various characteristics about the window in question, such as its geometry, position, size, depth, class, name, id, and more. The depth value indicates the number of bits per pixel used to represent the colors of the window. xwininfo is part of the X Window System, which is a graphical user interface system for Unix-like operating systems. xwininfo can be useful for debugging, testing, or scripting purposes.

The other options are incorrect because they are either invalid commands or do not show the color depth of the X Server:

xcd is not a valid command in Linux. It may be confused with cd, which is used to change the current working directory.

xcdepth is not a valid command in Linux. It may be confused with xrandr, which is used to change the screen resolution and orientation.

xcolordepth is not a valid command in Linux. It may be confused with xcalib, which is used to load, alter, and query the color profile of the X display.

cat /etc/X11 is not a command, but a directory. cat is used to concatenate files and print them to the standard output. /etc/X11 is a directory that contains configuration files for the X Window System. However, these files do not necessarily show the current color depth of the X Server, as it may be overridden by other settings or options. References:

https://bing.com/search?q=command+to+show+color+depth+of+X+Server

https://x.org/releases/X11R7.5/doc/man/man5/xorg.conf.5.html

The set command is used to display or modify the shell variables and functions in the current shell. When used without any arguments, it prints the names and values of all shell variables, including environment variables and user-defined variables, in alphabetical order. The output also includes the shell options and the positional parameters. The set command can be used in any POSIX-compliant shell, such as bash, zsh, ksh, etc123.

The other options are not correct because:

env is used to print or modify the environment variables, not the shell variables. It does not show the user-defined variables or the shell options. It can also be used to run a command in a modified environment45.

env -a is an invalid option for the env command. The -a option is not supported by the env command in any standard or common implementation45.

echo $ENV is used to print the value of the environment variable ENV, not the list of all shell variables. The ENV variable is usually set to the name of a file that contains commands or aliases to be executed by the shell. It is mainly used by the ksh and some versions of bash .

References: 1: How can I list all shell variables? - Unix & Linux Stack Exchange 2: 2.1 Command Line Basics - Linux Professional Institute Certification … 3: set - The Open Group Base Specifications Issue 7, 2018 edition 4: How to set and list environment variables on Linux 5: env - The Open Group Base Specifications Issue 7, 2018 edition : What is the difference between .bash_profile and .bashrc? - Unix & Linux Stack Exchange : ENV - The Open Group Base Specifications Issue 7, 2018 edition