To diagnose potential issues with domain name resolution, you might use the "dig" command. "dig" (Domain Information Groper) is a powerful command-line tool for querying DNS (Domain Name System) servers and obtaining detailed information about DNS records and name resolution, making it useful for troubleshooting DNS-related problems.

The "s" in a permission string like "drwxr-sr-x" signifies the "Set user or group ID" permission. When set on an executable file, it allows the user who runs the file to temporarily inherit the permissions of the file's owner or group, depending on where it's set (user or group ID).

The 'vm.swappiness' parameter controls the balance between swapping out and caching application data in Linux. It determines how often the system will swap data from RAM to disk and vice versa. A lower value (e.g., 0) keeps more data in RAM, while a higher value (e.g., 100) swaps data out more aggressively.

For optimizing database performance, you might adjust the vm.dirty_ratio parameter to control disk caching behavior. This parameter in the sysctl settings defines the percentage of system memory that can be filled with dirty data pages before the kernel starts writing them to disk, which can impact database I/O performance.

SELinux (Security-Enhanced Linux) enforces mandatory access controls at the kernel level in Linux. It provides a powerful and flexible security framework that allows administrators to define fine-grained access policies for processes, files, and resources on a system.

The Arch distribution is known for its advanced package management system called "pacman." Arch Linux uses a rolling release model and the pacman package manager for installing, updating, and managing software packages.

The primary protocol used by NFS (Network File System) for sharing files is NFS itself. NFS is a network protocol specifically designed for sharing files and directories among networked computers. It is commonly used in Unix and Linux environments.

A valid way to declare a variable in Bash is by using the format 'myVar=42'. This assigns the value 42 to the variable 'myVar'. The '$' symbol is used to reference the variable.

The purpose of the $? variable in a shell script is to store the script's exit status. A value of 0 typically indicates success, while non-zero values indicate different types of errors or failures. This is essential for error checking and script control flow.

To see the history of commands executed in the terminal, you would use the "history" command. This command displays a list of previously executed commands, making it easier to re-run or recall commands that were used in the past.