host.py

from argparse import ArgumentParser
import socket


def dns_lookup(hostname: str) -> str:
    return socket.gethostbyname(hostname)


if __name__ == '__main__':
    parser = ArgumentParser()
    parser.add_argument('input', type=str)

    args = parser.parse_args()

    with open(args.input, mode='r') as f:
        hostname = f.readline()
        while hostname:
            hostname = hostname.replace('\n', '')
            try:
                ip = dns_lookup(hostname)
            except:
                ip = 'dne'
            print(hostname, '\t', ip)
            hostname = f.readline()