Registrar Domains.

Glossary

Domain glossary

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The 15 domain terms you meet on this site and in your dashboard, each in plain English with the RFC, IANA or ICANN page it rests on.

A

Auth code(EPP code, authInfo, transfer code)

A password attached to a domain that proves the holder agrees to move it to another registrar. It is assigned when the domain is created, and it can change later. The current registrar must give it to the domain holder on request, and must not hold it back over a payment dispute.

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D

DNS(Domain Name System)

The Internet's naming system, which turns a name such as example.com into the data a computer needs, such as an IP address. Names form a tree: each name is a list of labels read from the most specific to the root. Name servers hold the data for parts of the tree, and resolvers ask them for answers.

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DNSSEC(DNS Security Extensions)

Extensions to the DNS that sign its data, so a resolver can check that an answer comes from the zone owner and was not changed on the way. It does not encrypt queries or answers, so it does not make them private. Each signed zone publishes its public keys, and the parent zone vouches for them with a DS record.

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DS record(Delegation Signer)

A DNS record that links a signed zone to its parent, so the chain of trust in DNSSEC can continue down the tree. It holds a digest of one of the zone's public keys (a DNSKEY record), with its key tag and algorithm number. It lives in the parent zone: the DS record for example.com sits in the com zone, not in the example.com zone.

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E

EPP(Extensible Provisioning Protocol)

The protocol a registrar uses to create, renew, transfer and update domains at the registry. Messages are XML, and separate documents map them to domains, hosts and contacts. The status values on a domain, such as clientTransferProhibited, come from EPP.

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I

IANA(Internet Assigned Numbers Authority)

The body that coordinates the Internet's globally unique identifiers: the DNS root zone, IP address blocks and protocol numbers. It keeps the Root Zone Database, which lists every top-level domain and the registry that runs it. Public Technical Identifiers, an affiliate of ICANN, performs the IANA functions.

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ICANN(Internet Corporation for Assigned Names and Numbers)

A non-profit organization that coordinates the Internet's unique identifiers, such as domain names and IP addresses, across the world. It sets the policies that generic top-level domains follow, for example the rules for moving a domain between registrars. It accredits registrars, which then sign its Registrar Accreditation Agreement.

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IDN(internationalized domain name, Punycode, A-label, U-label)

A domain name with at least one label in characters beyond the ASCII letters, digits and hyphen, such as café.fr. The DNS itself stores the ASCII form, called an A-label, which starts with xn-- and comes from the Unicode form (the U-label) through the Punycode algorithm. Registries must limit which characters they accept, because some characters look alike.

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N

Nameserver(name server, NS record)

A server that holds the DNS data of one or more zones and answers queries about them. The nameservers set for a domain at the registry tell the world which servers hold its records. To move a domain's DNS to another provider, you change its nameservers.

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R

RDAP(Registration Data Access Protocol)

The protocol that returns the registration data of a domain, such as its registrar, dates and nameservers, over HTTP with answers in JSON. It replaces WHOIS: since 28 January 2025, generic top-level domains must offer RDAP and no longer need to offer WHOIS. A bootstrap file published by IANA tells a client which server to ask for each top-level domain.

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Registrar

A company that registers domains for customers and manages them at each registry. To sell names in generic top-level domains, a registrar needs accreditation from ICANN and signs its Registrar Accreditation Agreement.

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Registrar lock(clientTransferProhibited, transfer lock)

A status on a domain, clientTransferProhibited, that tells the registry to reject any request to move the domain to another registrar. Your registrar sets and removes it for you, and it helps stop a transfer you did not ask for. To transfer the domain, ask your registrar to remove the lock first.

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Registry(registry operator)

The organization that runs a top-level domain: it keeps the list of every name under it and publishes the zone. Registrars send their orders to the registry, which sets the rules for its extension. The IANA Root Zone Database names the registry of each top-level domain.

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T

TLD(top-level domain, gTLD, ccTLD, extension)

The last label of a domain name, such as com in example.com. Generic TLDs (gTLDs) include .com and .org, and country-code TLDs (ccTLDs) such as .fr use the two-letter country codes of ISO 3166. The IANA Root Zone Database lists every TLD and its registry.

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W

WHOIS

An old query protocol that returns registration data about a domain as plain text. It has no standard data format, no internationalization and no strong security. RDAP replaces it for generic top-level domains.

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