DNS Lookup for Mac

$ dig example.com MX
$ nslookup example.com

What it’s for

DNS turns names like example.com into the addresses computers connect to, and holds other records too: where a domain’s mail goes, who may issue its certificates, which servers are in charge of it. DNS Lookup asks for any of them, like dig in Terminal.

Use it when

• A website or email doesn’t work, and you want to know whether its name resolves.
• You changed a DNS record and want to check what it says now.
• You want to compare what your router’s DNS answers with a public resolver.

Reading the result

Enter a domain, pick a Record Type and click Lookup. Each answer shows its type, value and TTL: the number of seconds a resolver may keep the answer before it must ask again. Common Records asks for the usual types at once.

• A and AAAA are the IPv4 and IPv6 addresses.
• CNAME says the name is another name’s alias.
• MX names the mail servers, lowest priority number first.
• TXT holds text, such as the SPF and verification records email and services use.
• NS and SOA name the servers responsible for the domain.

What you might see

• Domain does not exist (NXDOMAIN). The name isn’t registered, or there’s a typo.
• The domain exists but has no records of this type. Try another type, or Common Records.
• SERVFAIL or REFUSED. The server couldn’t or wouldn’t answer. Try a different server.
• The query timed out, against a server on your network: Netutilus may need Local Network access. A hint appears when it looks that way.

Options worth knowing

• Custom DNS asks a server of your choice. Google, Cloudflare, Quad9, OpenDNS and AdGuard are asked over encrypted DNS (DNS over HTTPS). Any other address, such as your router or a Pi-hole, is asked directly.
• Right-click a record to copy it.

Related

• DNS, how names are resolved.
• DNS Propagation, to compare many resolvers at once.
• A website won’t open.