What is nslookup?
nslookup (short for “name server lookup”) is a command‑line tool that asks DNS servers for information about domain names. It lets you see the IP address a website points to, or find out which mail server handles email for a domain.
Let's break it down
- nslookup - the program you run.
- Domain name - the human‑readable address like example.com.
- DNS server - a computer that stores the mapping between domain names and IP addresses.
- Query - the question you ask the DNS server (e.g., “What IP does example.com have?”).
When you type
nslookup example.com, the tool contacts a DNS server, sends the query, and shows you the answer.
Why does it matter?
Understanding where a domain points helps you:
- Verify that a website is reachable.
- Troubleshoot network problems (wrong IP, DNS misconfiguration).
- Check security (ensure a domain isn’t pointing to a malicious IP).
- Learn how the internet translates names into numbers.
Where is it used?
- Network troubleshooting by IT staff or home users.
- Web developers checking that a new site’s DNS records are correct.
- Security analysts investigating suspicious domains.
- System scripts that need to resolve hostnames automatically.
Good things about it
- Simple to use; works on Windows, macOS, Linux.
- Provides both forward (name → IP) and reverse (IP → name) lookups.
- Lets you specify a particular DNS server to query.
- No installation needed on most operating systems.
Not-so-good things
- Limited to basic queries; doesn’t show all DNS record types as clearly as newer tools like
dig. - Output can be cryptic for absolute beginners.
- Some modern DNS features (DNSSEC validation, IPv6 specifics) are harder to see.
- In some environments, firewalls block DNS queries, making the tool unusable without extra configuration.