Domain Name Lookup
Simple forward and reverse Domain Name System (DNS) lookups.
Monitor Domain Name Lookup automatically
Simple forward and reverse Domain Name System (DNS) lookups. NetTests can run this check on a schedule, preserve historical results, compare changes over time, and alert you the moment something breaks.
Start monitoring free → See all monitoring productsFrequently Asked Questions
What makes nslookup different from dig or host?
nslookup predates both — it's the one DNS lookup tool that ships natively on Windows as well as Unix/Linux, which is why it's often the first one people learn. Its default output is simpler than dig's (just the answer, not the full response sections), and it has an interactive mode for running several lookups against the same server without retyping it each time.
Does nslookup behave the same on Windows and Linux?
The core forward/reverse lookup behavior is the same, but flag syntax differs — Windows nslookup uses set type=MX-style interactive commands, while the Unix version accepts -type=MX on the command line. This tool matches the Unix/BIND behavior. If you're troubleshooting a Windows machine specifically, run nslookup locally there too — Windows' own resolver cache can produce different results than a query sent from here.
What DNS record types should I know?
- A — IPv4 address of the domain.
- AAAA — IPv6 address.
- CNAME — alias pointing to another hostname.
- MX — mail server(s) for the domain.
- TXT — free-text records; used for SPF, DKIM, domain verification.
- NS — nameservers authoritative for the domain.
- SOA — start-of-authority; holds the primary NS and serial number.
- PTR — reverse DNS; maps an IP to a hostname.
What is TTL and why does it matter?
Time To Live (TTL) is the number of seconds resolvers are allowed to cache a Domain Name System (DNS) record. A TTL of 300 means the record may be cached for up to 5 minutes. Lower TTLs allow faster propagation of changes; higher TTLs reduce DNS query load but mean old records stick around longer after a change.
Why do I get different results from different resolvers?
Results can differ due to caching (each resolver may have cached a different version), geo-DNS (some Content Delivery Networks (CDNs) return different IPs based on the resolver's location), or propagation delays after a recent Domain Name System (DNS) change. Use the DNS Propagation tool to query many resolvers simultaneously.