def get_rdns(ip)

get_rdns.py

import socket

# Function/arguments: get_rdns(ip)
# Description:        Perform a reverse DNS query for the passed-in IP address.
# Returns:            String: the reverse DNS name, or ''.
def get_rdns(ip):
    try:
        result = socket.gethostbyaddr(ip)[0]
    except socket.herror:
        # print 'Unable to get rDNS for', ip
        result = ip
    return result