I'm in need of a scriptable tool that can handle large batches—around 100,000 IP addresses—to extract domain names and ISPs. I've tried using nslookup for testing, but it hasn't been very reliable. This data will help me cross-reference our traffic logs for a quick overview of the sites and sources being interacted with, both incoming and outgoing. Any recommendations on tools or approaches that work well for this?
2 Answers
You might want to consider moving your internal DNS over to Cloudflare Gateway. It provides a nice chart of commonly accessed domains along with filter and blocklist options. Just set up a tunnel between your network and Cloudflare and change your DNS servers to point to theirs.
This is a classic use case for scripting. A simple bash or Python script can do this easily! For example, you could loop through your list of IPs and use the `dig` command to get their hostnames. Just format the output into CSV, and you'll be good to go!
That's a solid method! But keep in mind that it might not give you as much detailed information as you might need.