Domain Name Resolution on a Linux machine

An application running on a Linux machine, such as a web browser or email client, requests the IP address of a domain name (e.g., example.com).
/etc/hosts: The system checks the /etc/hosts file to see if the domain name and corresponding IP address are listed there. If a match is found, the IP address is returned immediately, and the resolution process is complete.
/etc/resolv.conf: If the domain name is not found in /etc/hosts, the system proceeds to the DNS resolver configuration. The system checks the /etc/resolv.conf file to determine the DNS servers to query. This file typically contains one or more nameserver lines, each specifying the IP address of a DNS server. The system will query these DNS servers in the order they are listed.
/etc/nsswitch.conf: The system looks at the /etc/nsswitch.conf file to determine the order of name resolution services to consult. The "hosts" line in this file specifies the order, usually starting with "files" (for /etc/hosts) and "dns" (for DNS servers).
Querying DNS Servers: The system sends a DNS query to the first DNS server specified in /etc/resolv.conf for the IP address of the domain name.
DNS Resolution: The DNS server processes the query and attempts to resolve the domain name to an IP address. If the DNS server has the information in its cache, it returns the IP address immediately. Otherwise, it recursively queries other DNS servers until a response with the IP address is obtained. The response is then returned to the Linux system.
Application Response: The Linux system receives the IP address from the DNS server. The application can now use the obtained IP address to establish a connection with the desired server.

These steps provide a high-level overview of the name resolution process in Linux, referencing the relevant files involved in the configuration. Keep in mind that there can be additional complexities and variations depending on the specific configuration and network setup of your Linux distribution.