Python Code To Determine If Tld Exists, Prompt Again If Not?

This is an additional question in regards to this post: Python raw_input with forced TLD? I have a check in place to see if a string ends with a TLD, TLD = ('.com', '.info', '.org

Solution 1:

Something like this:

TLD = ('.com', '.info', '.org', '.net')
hostName = raw_input(":").lower()
whilenot hostName.endswith(TLD):
    print"Incorrect input, Try again!"
    hostName = raw_input(":").lower()

Demo:

:foo.bar
Incorrect input, Try again!
:google.in
Incorrect input, Try again!
:yahoo.com

Solution 2:

Actual DNS lookup to test a TLD

Ohh, while we are at it, maybe a short snippet to actually test TLD's against the DNS servers might become handy. I'm using the dnspython module from the Nominum guys:

import dns.resolver

deftestTLD(tld):
    try:
        dns.resolver.query(tld + '.', 'SOA')
        returnTrueexcept dns.resolver.NXDOMAIN:
        returnFalsefor tld in ('com', 'org', 'klonk', 'dk'):
    print"TLD \"{tld}\" exists: {bool}".format(tld=tld, bool=testTLD(tld))

and it runs like this:

TLD "com" exists: True
TLD "org" exists: True
TLD "klonk" exists: False
TLD "dk" exists: True