[Tutor] Socket Module

[Nym City]

Hello,
I am working on a 2 individual programs. In the first program, I am taking in a list of domains in .csv format and want to get the associated IPs. 
In the second program, I want to import in a list of IP .csv and than get the associated domains out.
Eventually I want to get both of the above programs to write out to the same .csv file that they are reading from- in the next column. But I am not there yet.
Doing research I came across the following example:http://python.about.com/od/pythonstandardlibrary/qt/dnscheck.htm
>From the link above, doing domain -> IP would be easier to begin with. Here are the two variations of my code:
Variation 1:
import csv
import socket

domains = open('top500domains.csv', 'r')
for domain in domains:
    domain = socket.gethostbyname(str(domains))
    print(domains + "\n")
For the code above, I receive the following error on run: socket.gaierror: [Errno -2] Name or service not known.
Variation 2:
import csv
import socketdomains = []

with open('top500domains.csv', 'r') as f:
    for line in f:
        line = line.strip()
        domains.append(line)

hostbyname_ex = socket.gethostbyname_ex(str(domains))
print(hostbyname_ex)
I receive the same error as the first variation. 
Please share your advice and let me know what I am doing wrong. The top500domains.csv list is attached. 

Thanks in advance!




 Thank you.