sca_sles15 SUSE Certified Administrator in Enterprise Linux 15 Questions and Answers

The file that contains the list of DNS servers SLES will contact is /etc/resolv.conf. This file specifies one or more nameserver addresses that will be used to resolve hostnames to IP addresses. It may also contain other options such as search domains, sort lists, etc. The /etc/resolv.conf file can be generated automatically by network configuration tools or edited manually by the administrator. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-network-dns.html#sec-network-dns-resolv.conf

The command that gives you a real-time view of the processes running on your system by giving you a continuously updated list is top. The top command will display various information about system performance and resource usage, such as CPU load, memory usage, swap usage, etc., as well as a list of processes sorted by CPU utilization by default. You can use various keyboard commands to interact with top and change its behavior and output. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-cli-processes.html#sec-cli-processes-top

The -U option will install a package whether or not a previous version of the package is already installed. If a previous version exists, it will be upgraded. The -F option will install a package only if a previous version of the package is already installed. It will not install a new package.References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-sw-cl.html#sec-rpm-commands

The bash commands that result in a valid arithmetic expansion are:

• TOTAL=$[8/2]
• TOTAL=$((5+2))
• ((TOTAL++))

Arithmetic expansion is a bash feature that allows you to perform integer calculations and assign or use the result in a command or expression. There are two syntaxes for arithmetic expansion: [expression]and((expression)). The expression can contain variables, operators, parentheses, etc. The ((expression)) syntax can also be used without the $ sign for assignments or conditional tests. References: https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-bash.html#sec-bash-arithmetic

The command that allows you to create an alias command is alias. The alias command can be used to define a short name or abbreviation for another command or sequence of commands. The syntax of the alias command is alias name=‘command’. For example, alias c=‘clear’ will create an alias named c for the clear command. You can then type c to run the clear command. To remove an alias, you can use unalias name. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-bash.html#sec-bash-alias

The network interface type supported by SLES that is used for link aggregation is bond. Link aggregation is a technique that combines multiple physical network interfaces into one logical interface for increased bandwidth and redundancy. A bond interface can use different modes and options to balance traffic and handle failures. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-network-bonding.html

The commands that could be used to determine the proper syntax for the cp command are man cp, cp --help, and info cp. These commands will display the manual page, help message, or info page for the cp command, respectively. They will provide information about the usage, options, arguments, examples, and other details of the cp command. The other commands are either invalid or unrelated to cp. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-cli-help.html

https://en.wikipedia.org/wiki/Virtual_Network_Computing#:~:text=VNC%20by%20default%20uses%20TCP,Java%2Denabled%20 web%2Dbrowser.

VNC by default uses TCP port 5900+N,[6][7] where N is the display number (usually :0 for a physical display). Several implementations also start a basic HTTP server on port 5800+N to provide a VNC viewer as a Java applet, allowing easy connection through any Java-enabled web-browser. Differentport assignments can be used as long as both client and server are configured accordingly. A HTML5 VNC client implementation for modern browsers (no plugins required) exists too.[8]

The default port a VNC Client uses to connect is TCP 5901. This port corresponds to the first display number (:1) of the VNC server. Each display number has its own port number, starting from 5900. For example, display :2 uses port 5902, display :3 uses port 5903, and so on. The user can specify a different port number if needed. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-vnc-connect.html

After the kernel has been loaded during the boot process, udev will handle hardware detection. Udev is a device manager that creates device nodes and symlinks in /dev based on rules and events. It also loads kernel modules and applies persistent device names and permissions. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-boot-initrd.html#sec-boot-initrd-udev

Assuming the default value for umask, which is 022, the permissions on new files would be set to 644 and the permissions on new directories would be set to 755. The umask value is subtracted from the base permissions of 666 for files and 777 for directories to determine the actual permissions. For example, 666 - 022 = 644 for files and 777 - 022 = 755 for directories. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-file-permissions.html#sec-file-permissions-umask

Log file rotation is the process of compressing or deleting old log files to save disk space and improve performance. The /etc/logrotate.conf file controls the global settings for log file rotation, such as frequency, size limit, compression method, etc. The /etc/logrotate.d/ directory contains configuration files for specific log files that can override the global settings in /etc/logrotate.conf. The /usr/sbin/logrotate program is used to perform log file rotation according to the configuration files. It is usually invoked by a cron job in /etc/cron.daily/logrotate. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-logrotate.html

The file that contains the ntp configuration is /etc/ntp.conf. This file specifies the ntp server or peer addresses, synchronization options, access restrictions, logging settings, and other parameters for the ntp daemon (ntpd) that provides time synchronization services on a Linux system. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-ntp-config.html

The /etc/fstab file contains information about file systems that need to be mounted at boot time or on demand. It specifies the device name, mount point, file system type, mount options, dump frequency, and fsck order for each file system. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-storage-mounting.html#sec-storage-mounting-fstab

The name of the system logging facility in SUSE Linux Enterprise is syslog-ng. It is a flexible and scalable implementation of the syslog protocol that can handle various types of log messages from different sources and destinations. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-syslog.html

Firewalld uses two separated configuration sets, runtime, and permanent configuration.

The runtime configuration is the actual running configuration and it is not persistent on reboots. When the firewalld service starts it loads the permanent configuration which becomes the runtime configuration.

https://www.supportsages.com/everything-you-need-to-know-about-firewalld/#:~:text=Firewalld%20uses%20two%20separated%20configuration,which%20becomes%20the%20runtime%20configuration .

Firewalld maintains two separate configurations: runtime and permanent. The runtime configuration is the current state of the firewall that is applied to the system. It can be changed by various commands and tools without affecting the permanent configuration. The permanent configuration is the persistent state of the firewall that is stored in configuration files. It can be changed by various commands and tools with the --permanent option. The permanent configuration will take effect after reloading firewalld or rebooting the system. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-firewall-firewalld.html#sec-firewall-firewalld-config

The command that will display the value of a variable named TMPDIR is echoTMPDIR.Theechocommandwillprintitsargumentstothestandardoutput.Thesign is used to reference the value of a variable in bash. If you omit the $ sign, echo will print the name of the variable instead of its value. If you use single quotes around the variable name, echo will also print the name instead of its value. If you use double quotes around the variable name, echo will print its value as expected. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-bash.html#sec-bash-variables

If the file1.txt file already exists in your home directory, the touch -7file1.txt command will change the access and modification times of the existing file1.txt file. The touch command can be used to create new empty files or update the timestamps of existing files. The -7 option specifies that only one timestamp should be changed instead of both. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-cli-touch.html

The configuration files that have a format that is compatible with the system logging facility in SUSE Linux Enterprise are /etc/syslog.conf and /etc/rsyslog.conf. These files contain rules that specify how to filter and process log messages from different sources and destinations. The /etc/syslog.conf file is used by the traditional syslogd daemon, while the /etc/rsyslog.conf file is used by the more advanced rsyslogd daemon. SUSE Linux Enterprise uses rsyslogd by default, but it can also read /etc/syslog.conf for backward compatibility. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/cha-syslog.html#sec-syslog-config