How can you map DNS/host names to their IPs at scale?

Question

We're trying to look at a fairly large httpd config and find the all the IPs/ports we'd have to allow through a new firewall.

Ports are easy, but resolving all the DNS names to the (multiple) IPs they may have and outputting it in easy-to-consume manner seems hard.

What's the best way?

Answer 1

There may be other ways to achieve this. But the most elegant way we found was using python's socket library.

You can get all the info in a one liner, and extract it into a list in another line. It's fast, short, readable, and easy to put in a loop against a ton of records.

The Code

import socket

net_info = socket.getaddrinfo("stackoverflow.com", None)
ip_list = set([x[0] for x in [x[4] for x in net_info]])

print(ip_list)

Output

{'151.101.129.69', '151.101.1.69', '151.101.193.69', '151.101.65.69'}