In Linux, the hashed password information for users is stored in the /etc/shadow file. This file contains encrypted password hashes and other security-related information, such as password expiration dates, for user accounts. It is essential for protecting user credentials.

The service responsible for resolving domain names to IP addresses in Linux is the DNS (Domain Name System). DNS servers maintain a database of domain name-to-IP address mappings and help in translating human-readable domain names to numeric IP addresses, enabling network communication.

To compare two numbers in Bash and check if they're equal, you'd use the == operator within a conditional statement. The == operator is used for equality comparison in Bash.

The file in Linux used to configure network interfaces and typically found in the /etc/network/ directory is the "interfaces" file. This file contains information about network interfaces and their settings, allowing you to define and manage network connections on your system.

To find all occurrences of the word "error" in a directory with log files, you would primarily use the grep command. grep is a powerful tool for searching text and regular expressions in files and can be used to quickly locate specific content, like error messages, within files.

The correct command to send ICMP echo requests to test network connectivity is 'ping.' When you run 'ping' followed by an IP address or hostname, it sends ICMP echo requests to that address and waits for responses, allowing you to determine if the network connection is working.

In Bash scripting, the '$' symbol is used to execute a command. When you prefix a command with '$', it's interpreted as a variable and executed. For example, $ ls would execute the 'ls' command.

In Debian and its derivatives, the primary tool used for package management is APT (Advanced Package Tool). APT is a package management system that allows users to install, upgrade, and remove software packages on Debian-based systems.

The nslookup command can be used to query DNS (Domain Name System) records, including MX (Mail Exchange), NS (Name Server), and SOA (Start of Authority) records. It's a valuable tool for DNS troubleshooting and network diagnostics.

To change or set the UUID of a filesystem in Linux, you would use the tune2fs command. This command allows you to modify various filesystem parameters, including the UUID.