DNS Tools (dig / nslookup)

Definition

Command-line tools used for querying Domain Name System (DNS) servers to resolve hostnames to IP addresses, or vice-versa.

Explain Like I'm New

Asking the internet phonebook a direct question. You ask 'Where does google.com point?', and it tells you the exact IP address and how it found it.

Real World Example

A company changes their website's server. Customers complain they still see the old website. The admin types `dig mycompany.com`. The output proves that the global DNS records have not updated yet.

Common Use Cases

•Verifying domain migrations
•Troubleshooting DNS caching

Interview Questions

basic

Which command is older and generally considered deprecated: `dig` or `nslookup`?

intermediate

What does it mean to query a specific DNS server using `dig @8.8.8.8 example.com`?

Flash Cards

Question

Which is older?

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Answer

`nslookup` is the older, legacy tool. `dig` is the modern, much more verbose standard.

Question

What does @ do?

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Answer

It tells `dig` to ignore your computer's local internet provider settings, and instead ask Google's public DNS server (8.8.8.8) directly what it thinks the IP address is.