Linux / Unix: Find Out DNS Server IP Address / Names

How do I find out my DNS server IP address assiged my my ISP under Unix or Linux operating system using command prompt? How do I find preferred dns server under Debian / Ubuntu / Fedora Linux desktop system?

Under Unix or Linux operating systems the resolver is used (set of routines in the C library) that provide access to the Internet Domain Name System (DNS). The resolver configuration file is located at /etc/resolv.conf location and it contains information that is read by the resolver routines the first time they are invoked by a process. Use the cat command or grep command to find out your dns server addresses as follows:

cat /etc/resolv.conf

Sample outputs:

# Generated by NetworkManager
nameserver 192.168.1.2
nameserver 192.168.1.3

In this example my dns server address are 192.168.1.2 and 192.168.1.3 in dot notation that the resolver should query. Currently name servers may be listed, one per keyword. If there are multiple servers, the resolver library queries them in the order listed. If no nameserver entries are present, the default is to use the name server on the local machine. The grep command can be used as follows:
$ grep --color nameserver /etc/resolv.conf
Sample outputs:

Fig.01: Linux / Unix: Find Preferred Dns Server Command

Posted by: SXI ADMIN

The author is the creator of SXI LLC and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.