man fdnsname (Commandes) - resolve an IPv4 or IPv6 address to a hostname
NAME
fdnsname - resolve an IPv4 or IPv6 address to a hostname
SYNOPSIS
fdnsname <IP address>
DESCRIPTION
fdnsname will attempt to look up a single hostname for IP address (which is an IPv4 address in dotted-quad format or an IPv6 address in colon-seperated format). If one is found, it is printed to standard output and the program exits with return code 0. If not, nothing is printed and the program exits with return code 1.
AUTHOR
Ian Gulliver <ian@penguinhosting.net>