The Domain Name System (DNS) is the most widely used service for translating domain names into IP addresses and vice versa. The DNS service by default runs on port 53. We can use the Nmap syntax, as follows, to enumerate the DNS service:

nmap -p 53 -T4 -A -v <Target IP address>

The following screenshot shows that the type of DNS server on the target system is ISC bind version 9.4.2: