Common DNS queries like
ping will first get the IP of a hostname if it exists in /etc/hosts.
Multiple tools on Linux can do the “reverse” checking using /etc/hosts file. For example, if we have a line
192.0.2.1 test in the
/etc/hosts, we can query the host name from the IP as follows.
getent hosts: When one or more arguments are provided, it will pass each key to
gethostbyname2(), depending on whether a call to
inet_pton() indicates that the argument is an IPv6 or IPv4 address or not, and display the result.
$ getent hosts test 192.0.2.1 test
host is given a dotted-decimal IPv4 address or a colon-delimited IPv6 address,
host will by default perform a reverse lookup for that address.
$ host 192.0.2.1 184.108.40.206.in-addr.arpa domain name pointer test.