The DNS Lookup API returns every record of a domain, or the name behind an IP address

Send a domain and it returns the A, AAAA, CNAME, MX, NS, TXT, CAA and SOA records the name publishes, in one call. It also works out two plain labels from them: the mail provider, read from the MX hosts, and the DNS host, read from the name servers. Send an IP address instead and it returns the reverse DNS (PTR) names. The flat classification block holds a count, the two labels and one text field per record type, and the structured records sit under insights.

Yes. The MX records come back with their priorities in order, and the mail provider is named in plain words, such as Google Workspace or Microsoft 365, so one call tells you where a domain's mail is handled. A domain that publishes a null MX, which says it accepts no mail, is flagged with null_mx: true instead of a provider.

Yes. Send an IPv4 or IPv6 address in the ip field, or in the domain field, and you get the PTR names published for it, with the reverse lookup name that was asked. An address with no PTR record is a free answer with the reason no_ptr. Private, loopback and internal addresses are refused with a 400 error before anything is looked up.

From DNS itself. 1Lookup asks the question any resolver asks, for all eight record types at once, and returns what the name publishes at that moment. No database of past records sits behind it, so the answer is the live record, and every result carries the day it was read in checked_at.

2 credits per lookup that finds something, about $0.01 on the Starter plan. A domain with records and an IP address with a reverse name are billed. A name that does not exist, a name with none of the eight types and an IP address with no PTR record cost nothing, and neither does a lookup the DNS system could not answer.

Four cases cost nothing. The name is not in DNS (found: false, reason no_such_domain). The name exists but has none of the eight record types (no_records). The IP address has no reverse name (no_ptr). Or every query timed out or failed, which returns a 503 with a Retry-After header, is never remembered, and is never reported as a name with no records.

A domain, a web address or an email address, cut down to the domain, or an IPv4 or IPv6 address. Subdomains are kept as written, because www.example.com and shop.example.com each have their own records, and names with an underscore such as _dmarc.example.com are allowed. A single word, an internal name such as localhost and a private address are refused with a 400 error and cost nothing.

From the hostnames the records point to. The mail provider is read from the endings of the MX hosts and the DNS host from the endings of the name servers. A zone that uses more than one DNS host shows each one found. Hosts that match no known provider read as custom, and a domain with no MX or no name servers has no label. It says where the records point, not what is inside anyone's account.

A result is remembered for 15 minutes, so a repeat of the same question returns the same answer at the same price. Send bypass_cache: true to read the name again straight away, for example right after you change a record.

Yes. Upload a CSV with a domain column, and an IP address in that column gets its reverse name. You get a row per name with Found, Mail Provider, DNS Host, Record Count, one column for each record type, PTR Names and Why Nothing Found. A name with nothing found is a free row. The price stays at the same credits per lookup that finds something.

It reads the eight record types listed and nothing else: no DNSSEC validation, no SRV or TLSA records, and no history of past records. It reads DNS from one place, so a zone that answers differently by region can read differently to a visitor, and it does not check propagation across many resolvers. SPF, DKIM and DMARC are interpreted by Email Authentication Check, which grades them.