Domains and DNS Glossary · Hosting & Cloud

.ai (Anguilla): Anguilla's ccTLD, whose registration sales Identity Digital manages under an agreement with the government (New gTLDs & ccTLDs).
.Brand: a TLD applied for by a company for its own brand, which can't be open to the public or run a sunrise and is a long operating commitment (New gTLDs & ccTLDs).
.io (British Indian Ocean Territory): the ccTLD whose future became uncertain when the UK agreed to transfer sovereignty over the Chagos Archipelago, the example of a ccTLD's country code itself being at risk (New gTLDs & ccTLDs).
ACPA in rem: an action under the US Anticybersquatting Consumer Protection Act against the domain name itself, filed where the registrar or registry is located when personal jurisdiction over the registrant can't be obtained (Domain Disputes).
Actionable evidence: information readily available to the registrar sufficient to make a reasonable determination of DNS Abuse, the point from which prompt action is measured (DNS Abuse at the Registrar).
Add Grace Period (AGP): the five days after a registration during which a registrar delete credits the fee, capped per registrar per month by the AGP Limits Policy since domain tasting (The Domain Lifecycle).
AGP Limits Policy: the consensus policy that bars registries from refunding Add Grace Period deletes above a monthly threshold per registrar per TLD (The Domain Lifecycle).
Alias record / CNAME flattening: provider features that answer at the zone apex with addresses resolved from a target name, working around the rule that a CNAME can't sit at the apex; they aren't zone data and don't transfer (DNS Hosting & DNSSEC).
Ambiguous outcome: an EPP command with no or a malformed response, whose success must not be assumed and has to be resolved by asking the registry (The Domain Data Model & EPP).
Apex CNAME problem: a CNAME can't coexist with other data, and the zone apex must hold SOA and NS records, so example.com itself can't be a CNAME to a load balancer or CDN (DNS Hosting & DNSSEC).
Auth code (AuthInfo): the per-domain secret the registrant gives the gaining registrar to authorize a transfer, which RFC 9154 says should be random, set only during a transfer and stored by the registry only as a hash (Transfers, Locks & Registrar Security).
Auto-Renew Grace Period: the period after expiry, when the registry has renewed the name automatically and billed the registrar, during which a registrar delete credits the renewal (The Domain Lifecycle).
Backorder: an order with a service that tries to register a pending-delete name the moment it drops (The Domain Lifecycle).
Bundled DNS: DNS given away free (Cloudflare, DigitalOcean, most registrars and hosts) as a way to win the zone for another product (DNS Hosting & DNSSEC).
CDS and CDNSKEY: records a signed child zone publishes to tell its parent which DS to hold, so the parent can scan and update the DS automatically (DNS Hosting & DNSSEC).
Change of Registrant: Part II of the Transfer Policy: a material change to a registrant's name, organization or email needs confirmation from both the prior and new registrant (Transfers, Locks & Registrar Security).
Change of Registrant lock: the 60-day inter-registrar transfer lock imposed after a change of registrant unless the registrant opted out (Transfers, Locks & Registrar Security).
Claims period: at least the first 90 days of general registration, when anyone registering a name matching a Trademark Clearinghouse mark gets a claims notice and the mark holder is told if they proceed (New gTLDs & ccTLDs).
clientHold: the EPP status a registrar adds so the registry stops publishing the name in the DNS, its suspension lever for non-payment and abuse; nothing below the name resolves (DNS Abuse at the Registrar).
Cloudflare Registrar: Cloudflare's retail registrar for its own customers, selling names at cost, at or below what registries and ICANN charge (ICANN, Registries & Registrars).
Consensus policies: ICANN policies that bind registries and registrars through their contracts, such as the Transfer Policy, the ERRP, the AGP Limits Policy, the UDRP and the Registration Data Policy (ICANN, Registries & Registrars).
Contact object: the EPP object (RFC 5733) for a person or organization, with a client-chosen ID, postal info, phone, email and an authInfo (The Domain Data Model & EPP).
Contention (gTLD round): applicants for the same string in one set, resolved in the 2026 round only by ICANN's auction or Community Priority Evaluation, with private auctions barred (New gTLDs & ccTLDs).
DNS Abuse: in the amended RAA and registry agreement, malware, botnets, phishing, pharming, and spam when it delivers one of the others (DNS Abuse at the Registrar).
DNS failover: answering with a secondary when the primary's health check fails, bounded by caching because resolvers keep the cached answer until its TTL expires (DNS Hosting & DNSSEC).
DNSSEC chain: a signed zone's DNSKEY and RRSIG records, its NSEC or NSEC3 denial records, and the DS at the parent that links its key into the chain of trust (DNS Hosting & DNSSEC).
Domain object: the EPP object (RFC 5731) for a registered name, whose attributes a registrar mirrors into its own tables (The Domain Data Model & EPP).
Domain tasting: registering names en masse, keeping the few that earned advertising revenue within the Add Grace Period and deleting the rest for a refund (The Domain Lifecycle).
Drop catching: registering a name the instant the registry purges it, where the first create wins, which drop catchers pursue by multiplying accreditations to multiply connections (The Domain Lifecycle).
DS record: the hash of a zone's key-signing key published at the parent, sent by the registrar to the registry over EPP's secDNS extension; a stale DS after a provider move is the most common DNSSEC outage (DNS Hosting & DNSSEC).
EPDP: the expedited policy development process ICANN ran to replace the Temporary Specification, whose Phase 1 became the basis of the Registration Data Policy (Registration Data & RDAP).
EPP: the Extensible Provisioning Protocol, the registry-registrar protocol (RFC 5730 and its object mappings) over TLS with mutual authentication (The Domain Data Model & EPP).
Expired name auction: a registrar selling a name it still sponsors during the auto-renew grace period, which should wait until the standard renewal window closes (The Domain Lifecycle).
Expired Registration Recovery Policy (ERRP): the consensus policy governing registrars between expiry and delete: notices before and after expiry, DNS interruption, and redemption (The Domain Lifecycle).
External and internal hosts: EPP host objects outside the registry's namespace (external) or subordinate to a domain in the registry (internal), whose superordinate domain must be known to the registry (The Domain Data Model & EPP).
Form of Authorization (FOA): the notice the losing registrar must send the registrant within 24 hours of a transfer request; the gaining registrar's FOA has gone unenforced since redaction hid the registrant's email (Transfers, Locks & Registrar Security).
Host object: the EPP object (RFC 5732) for a nameserver, with a name, a ROID, statuses and any IP addresses (The Domain Data Model & EPP).
ICANN accreditation fee: the fixed yearly fee each accredited registrar pays ICANN per accreditation (ICANN, Registries & Registrars).
ICANN transaction fee: the per-transaction-year fee a registrar pays ICANN on each new registration, renewal and transfer (ICANN, Registries & Registrars).
ICANN variable shared fee: a fixed yearly sum divided among all registrars, with forgiveness for qualified registrars (ICANN, Registries & Registrars).
KSK, ZSK and CSK: DNSSEC keys: the key-signing key signs only the DNSKEY set and its hash is the DS at the parent, the zone-signing key signs everything else and rolls without the parent, and a combined signing key does both (DNS Hosting & DNSSEC).
Launch phases: the sequence a new gTLD opens in: sunrise for trademark holders, claims notices, then general availability, often after an early-access period (New gTLDs & ccTLDs).
Lock (UDRP): the state a registrar must apply within two business days of a provider's verification request, blocking any change of registrant or registrar while the proceeding runs (Domain Disputes).
Lock (URS): the registry's lock within 24 hours of a URS complaint passing review, blocking all changes to the registration data, including transfer and deletion (Domain Disputes).
Metered DNS: DNS priced by a small per-zone fee and a per-million query price, with premium query types for routing (Route 53, Google, Azure) (DNS Hosting & DNSSEC).
Name-server reset: a registrar replacing a domain's host objects with its own so resolution moves to servers it controls, to serve a notice page or sinkhole (DNS Abuse at the Registrar).
NetBeacon: a free, centralized abuse reporting service from the DNS Abuse Institute that standardizes and enriches reports and routes them to registrars (DNS Abuse at the Registrar).
Notice of Breach: ICANN Compliance's formal breach notice with a cure deadline, the step before termination of a registrar's accreditation (ICANN, Registries & Registrars).
Pending Delete Period: the days after redemption ends without a restore, during which nothing can be done before the registry purges the name and it becomes available (The Domain Lifecycle).
Poll queue: the EPP message queue through which the registry tells the registrar about things it didn't do itself, such as transfer requests and registry actions (The Domain Data Model & EPP).
Premium names: names a registry prices in higher tiers, often with premium renewals, breaking the flat registry fee (ICANN, Registries & Registrars).
Primaries and secondaries: running a zone on two providers, one primary and one secondary pulling the zone by AXFR or IXFR on NOTIFY, with TSIG authenticating transfers (DNS Hosting & DNSSEC).
RAA (Registrar Accreditation Agreement): the contract between ICANN and each accredited registrar, setting fees, registration agreement terms, records, abuse duties and termination grounds (ICANN, Registries & Registrars).
RDAP: the Registration Data Access Protocol, HTTP and JSON lookups of registration data found through IANA bootstrap files, which replaced WHOIS as the definitive source for gTLD data (Registration Data & RDAP).
RDAP bootstrap: IANA's JSON registries pairing TLDs, IP prefixes and AS ranges with base RDAP URLs, matched right to left with the longest match winning (Registration Data & RDAP).
RDDS: registration data directory services: RDAP, and WHOIS where it still runs, which must publish the domain, registrar, abuse contacts, statuses, dates and nameservers (Registration Data & RDAP).
Redacted member: the RFC 9537 RDAP extension that lists each redacted field with its name, a JSONPath to it and the redaction method (Registration Data & RDAP).
Redemption Grace Period: the period after a registrar deletes a name outside the Add Grace Period, during which only the registrar can restore it (The Domain Lifecycle).
Registrar lock: clientTransferProhibited, usually with update and delete prohibitions, set by the registrar and removable by the account holder; it stops accidental transfers but not anyone who can log in (Transfers, Locks & Registrar Security).
Registration agreement: the contract between the registrar and its registrant, which must carry the terms the RAA and the registry require (ICANN, Registries & Registrars).
Registration Data Policy: the consensus policy governing what registrars collect, transfer to registries, publish and redact, disclose on request and retain (Registration Data & RDAP).
Registration Data Request Service (RDRS): ICANN's voluntary request router that passes disclosure requests to registrars that take part, deciding nothing and holding no data (Registration Data & RDAP).
Registry agreement: the contract between ICANN and a registry operator, requiring every registration to go through an ICANN-accredited registrar with non-discriminatory access (ICANN, Registries & Registrars).
Registry fee: the registry's wholesale price per name-year, paid by the registrar from its payment security at the transaction (ICANN, Registries & Registrars).
Registry lock: the serverTransferProhibited, serverUpdateProhibited and serverDeleteProhibited statuses set by the registry, released only after an out-of-band check, which protect against a compromised registrar account (Transfers, Locks & Registrar Security).
Registry Registrar Protocol (RRP): EPP's predecessor, a text protocol for the thin .com registry (ICANN, Registries & Registrars).
Registry service provider (RSP): the company that operates a TLD's technical back end for the brand on the contract, a separate business from the registry (New gTLDs & ccTLDs).
Registry-Registrar Agreement (RRA): the contract between a registry and each registrar covering the protocol, billing and the payment security that sets the registrar's credit (ICANN, Registries & Registrars).
Renew/Extend Grace Period: the days after an explicit renewal during which a registrar delete credits the renewal fee (The Domain Lifecycle).
Reseller (registrar): a seller of domain names under a wholesale registrar's accreditation, who pays no ICANN fees while the registrar answers to ICANN for it (ICANN, Registries & Registrars).
Restore: recovering a name from redemption in two EPP steps, a restore request and then a restore report with the registration data before and after (The Domain Lifecycle).
Result codes (EPP): four-digit EPP response codes whose first digit is success (1) or failure (2), which a registrar's code must branch on rather than on messages (The Domain Data Model & EPP).
Routing policies: DNS answer strategies such as simple, weighted, latency, geolocation, geoproximity, IP-based, failover and multivalue, priced as premium query types (DNS Hosting & DNSSEC).
SAC115: the Security and Stability Advisory Committee report proposing an interoperable approach to abuse handling, whose definition of DNS Abuse the contracts adopted (DNS Abuse at the Registrar).
SC-085v2: the CA/Browser Forum ballot requiring CAs to validate DNSSEC, when present, for CAA and domain validation lookups, so a broken signed zone fails certificate issuance (DNS Hosting & DNSSEC).
Sessions (EPP): EPP over TCP port 700 with TLS and mutual authentication, the registrar presenting a client certificate, under per-registry session limits (The Domain Data Model & EPP).
Signed Mark Data (SMD): the file from the Trademark Clearinghouse that a trademark holder needs to register during sunrise (New gTLDs & ccTLDs).
SOA record: the record at a zone's apex naming the primary server, contact, serial and the refresh, retry, expire and minimum timers (DNS Hosting & DNSSEC).
Sunrise: the launch phase restricted to trademark holders with a Signed Mark Data file, before general registration opens (New gTLDs & ccTLDs).
TDRP (Transfer Dispute Resolution Policy): the dispute policy for transfers, which only the gaining or losing registrar can file, with remedies that approve or reverse the transfer (Domain Disputes).
Temporary Specification: the ICANN Board's 2018 interim rule that redacted personal data from public registration data for the GDPR, later replaced by policy from the EPDP (Registration Data & RDAP).
Transaction identifiers (EPP): the client's <clTRID> and the server's <svTRID>, which together identify an EPP transaction and should both be logged and retained (The Domain Data Model & EPP).
Transfer Authorization Code (TAC): the Transfer Policy Review's name for the auth code: generated only on request, one-time use, valid for a fixed life and announced to the registrant when issued (Transfers, Locks & Registrar Security).
Transfer Grace Period: the days after a completed transfer during which a registrar delete credits the transfer fee (The Domain Lifecycle).
Transfer Pending Period: the days after a transfer request during which the losing registrar may approve or deny; if it does neither, the registry approves automatically (The Domain Lifecycle).
Transfer Policy: ICANN's consensus policy for inter-registrar transfers and changes of registrant, which gives registrants portability under fixed notice and approval clocks (Transfers, Locks & Registrar Security).
Transfer Policy Review: the GNSO review whose recommendations, adopted by ICANN's Board, rename and tighten the auth code, drop the gaining FOA and rename the losing FOA a Transfer Confirmation (Transfers, Locks & Registrar Security).
TTL: the time a resolver may cache a DNS record; a short TTL makes changes and failover fast and costs more queries (DNS Hosting & DNSSEC).
UDRP: ICANN's Uniform Domain-Name Dispute-Resolution Policy, a mandatory administrative proceeding in which a trademark owner can win cancellation or transfer of a name, nothing else (Domain Disputes).
UDRP elements: the three things a complainant must prove: the name is identical or confusingly similar to its mark, the registrant has no rights or legitimate interests, and the name was registered and used in bad faith (Domain Disputes).
UDRP freeze: the bar on transferring a disputed name to another holder or registrar while a UDRP is pending and for a period after it concludes (Domain Disputes).
UDRP providers: the approved dispute providers (ADNDRC, CIIDRC, the Czech Arbitration Court, Forum and WIPO) with which UDRP complaints are filed (Domain Disputes).
UDRP wait: the ten business days a registrar waits after a decision ordering transfer or cancellation, implementing it unless the registrant shows a file-stamped court complaint (Domain Disputes).
URS: the Uniform Rapid Suspension System, a faster, cheaper route for clear-cut infringement in new gTLDs, decided on clear and convincing evidence, with suspension as the only remedy (Domain Disputes).
URS remedy: the registry suspending the name for the rest of its registration period and pointing its nameservers at the provider's informational page (Domain Disputes).
WHOIS: the original public directory of registration data over TCP port 43, whose contractual obligation for gTLDs ended when RDAP became the definitive source (Registration Data & RDAP).
Zone (DNS): a contiguous part of the DNS namespace served from one set of name servers, with a single SOA and NS records at its apex (DNS Hosting & DNSSEC).

.ai (Anguilla): Anguilla's ccTLD, whose registration sales Identity Digital manages under an agreement with the government (New gTLDs & ccTLDs).
.Brand: a TLD applied for by a company for its own brand, which can't be open to the public or run a sunrise and is a long operating commitment (New gTLDs & ccTLDs).
.io (British Indian Ocean Territory): the ccTLD whose future became uncertain when the UK agreed to transfer sovereignty over the Chagos Archipelago, the example of a ccTLD's country code itself being at risk (New gTLDs & ccTLDs).
ACPA in rem: an action under the US Anticybersquatting Consumer Protection Act against the domain name itself, filed where the registrar or registry is located when personal jurisdiction over the registrant can't be obtained (Domain Disputes).
Actionable evidence: information readily available to the registrar sufficient to make a reasonable determination of DNS Abuse, the point from which prompt action is measured (DNS Abuse at the Registrar).
Add Grace Period (AGP): the five days after a registration during which a registrar delete credits the fee, capped per registrar per month by the AGP Limits Policy since domain tasting (The Domain Lifecycle).
AGP Limits Policy: the consensus policy that bars registries from refunding Add Grace Period deletes above a monthly threshold per registrar per TLD (The Domain Lifecycle).
Alias record / CNAME flattening: provider features that answer at the zone apex with addresses resolved from a target name, working around the rule that a CNAME can't sit at the apex; they aren't zone data and don't transfer (DNS Hosting & DNSSEC).
Ambiguous outcome: an EPP command with no or a malformed response, whose success must not be assumed and has to be resolved by asking the registry (The Domain Data Model & EPP).
Apex CNAME problem: a CNAME can't coexist with other data, and the zone apex must hold SOA and NS records, so example.com itself can't be a CNAME to a load balancer or CDN (DNS Hosting & DNSSEC).
Auth code (AuthInfo): the per-domain secret the registrant gives the gaining registrar to authorize a transfer, which RFC 9154 says should be random, set only during a transfer and stored by the registry only as a hash (Transfers, Locks & Registrar Security).
Auto-Renew Grace Period: the period after expiry, when the registry has renewed the name automatically and billed the registrar, during which a registrar delete credits the renewal (The Domain Lifecycle).
Backorder: an order with a service that tries to register a pending-delete name the moment it drops (The Domain Lifecycle).
Bundled DNS: DNS given away free (Cloudflare, DigitalOcean, most registrars and hosts) as a way to win the zone for another product (DNS Hosting & DNSSEC).
CDS and CDNSKEY: records a signed child zone publishes to tell its parent which DS to hold, so the parent can scan and update the DS automatically (DNS Hosting & DNSSEC).
Change of Registrant: Part II of the Transfer Policy: a material change to a registrant's name, organization or email needs confirmation from both the prior and new registrant (Transfers, Locks & Registrar Security).
Change of Registrant lock: the 60-day inter-registrar transfer lock imposed after a change of registrant unless the registrant opted out (Transfers, Locks & Registrar Security).
Claims period: at least the first 90 days of general registration, when anyone registering a name matching a Trademark Clearinghouse mark gets a claims notice and the mark holder is told if they proceed (New gTLDs & ccTLDs).
clientHold: the EPP status a registrar adds so the registry stops publishing the name in the DNS, its suspension lever for non-payment and abuse; nothing below the name resolves (DNS Abuse at the Registrar).
Cloudflare Registrar: Cloudflare's retail registrar for its own customers, selling names at cost, at or below what registries and ICANN charge (ICANN, Registries & Registrars).
Consensus policies: ICANN policies that bind registries and registrars through their contracts, such as the Transfer Policy, the ERRP, the AGP Limits Policy, the UDRP and the Registration Data Policy (ICANN, Registries & Registrars).
Contact object: the EPP object (RFC 5733) for a person or organization, with a client-chosen ID, postal info, phone, email and an authInfo (The Domain Data Model & EPP).
Contention (gTLD round): applicants for the same string in one set, resolved in the 2026 round only by ICANN's auction or Community Priority Evaluation, with private auctions barred (New gTLDs & ccTLDs).
DNS Abuse: in the amended RAA and registry agreement, malware, botnets, phishing, pharming, and spam when it delivers one of the others (DNS Abuse at the Registrar).
DNS failover: answering with a secondary when the primary's health check fails, bounded by caching because resolvers keep the cached answer until its TTL expires (DNS Hosting & DNSSEC).
DNSSEC chain: a signed zone's DNSKEY and RRSIG records, its NSEC or NSEC3 denial records, and the DS at the parent that links its key into the chain of trust (DNS Hosting & DNSSEC).
Domain object: the EPP object (RFC 5731) for a registered name, whose attributes a registrar mirrors into its own tables (The Domain Data Model & EPP).
Domain tasting: registering names en masse, keeping the few that earned advertising revenue within the Add Grace Period and deleting the rest for a refund (The Domain Lifecycle).
Drop catching: registering a name the instant the registry purges it, where the first create wins, which drop catchers pursue by multiplying accreditations to multiply connections (The Domain Lifecycle).
DS record: the hash of a zone's key-signing key published at the parent, sent by the registrar to the registry over EPP's secDNS extension; a stale DS after a provider move is the most common DNSSEC outage (DNS Hosting & DNSSEC).
EPDP: the expedited policy development process ICANN ran to replace the Temporary Specification, whose Phase 1 became the basis of the Registration Data Policy (Registration Data & RDAP).
EPP: the Extensible Provisioning Protocol, the registry-registrar protocol (RFC 5730 and its object mappings) over TLS with mutual authentication (The Domain Data Model & EPP).
Expired name auction: a registrar selling a name it still sponsors during the auto-renew grace period, which should wait until the standard renewal window closes (The Domain Lifecycle).
Expired Registration Recovery Policy (ERRP): the consensus policy governing registrars between expiry and delete: notices before and after expiry, DNS interruption, and redemption (The Domain Lifecycle).
External and internal hosts: EPP host objects outside the registry's namespace (external) or subordinate to a domain in the registry (internal), whose superordinate domain must be known to the registry (The Domain Data Model & EPP).
Form of Authorization (FOA): the notice the losing registrar must send the registrant within 24 hours of a transfer request; the gaining registrar's FOA has gone unenforced since redaction hid the registrant's email (Transfers, Locks & Registrar Security).
Host object: the EPP object (RFC 5732) for a nameserver, with a name, a ROID, statuses and any IP addresses (The Domain Data Model & EPP).
ICANN accreditation fee: the fixed yearly fee each accredited registrar pays ICANN per accreditation (ICANN, Registries & Registrars).
ICANN transaction fee: the per-transaction-year fee a registrar pays ICANN on each new registration, renewal and transfer (ICANN, Registries & Registrars).
ICANN variable shared fee: a fixed yearly sum divided among all registrars, with forgiveness for qualified registrars (ICANN, Registries & Registrars).
KSK, ZSK and CSK: DNSSEC keys: the key-signing key signs only the DNSKEY set and its hash is the DS at the parent, the zone-signing key signs everything else and rolls without the parent, and a combined signing key does both (DNS Hosting & DNSSEC).
Launch phases: the sequence a new gTLD opens in: sunrise for trademark holders, claims notices, then general availability, often after an early-access period (New gTLDs & ccTLDs).
Lock (UDRP): the state a registrar must apply within two business days of a provider's verification request, blocking any change of registrant or registrar while the proceeding runs (Domain Disputes).
Lock (URS): the registry's lock within 24 hours of a URS complaint passing review, blocking all changes to the registration data, including transfer and deletion (Domain Disputes).
Metered DNS: DNS priced by a small per-zone fee and a per-million query price, with premium query types for routing (Route 53, Google, Azure) (DNS Hosting & DNSSEC).
Name-server reset: a registrar replacing a domain's host objects with its own so resolution moves to servers it controls, to serve a notice page or sinkhole (DNS Abuse at the Registrar).
NetBeacon: a free, centralized abuse reporting service from the DNS Abuse Institute that standardizes and enriches reports and routes them to registrars (DNS Abuse at the Registrar).
Notice of Breach: ICANN Compliance's formal breach notice with a cure deadline, the step before termination of a registrar's accreditation (ICANN, Registries & Registrars).
Pending Delete Period: the days after redemption ends without a restore, during which nothing can be done before the registry purges the name and it becomes available (The Domain Lifecycle).
Poll queue: the EPP message queue through which the registry tells the registrar about things it didn't do itself, such as transfer requests and registry actions (The Domain Data Model & EPP).
Premium names: names a registry prices in higher tiers, often with premium renewals, breaking the flat registry fee (ICANN, Registries & Registrars).
Primaries and secondaries: running a zone on two providers, one primary and one secondary pulling the zone by AXFR or IXFR on NOTIFY, with TSIG authenticating transfers (DNS Hosting & DNSSEC).
RAA (Registrar Accreditation Agreement): the contract between ICANN and each accredited registrar, setting fees, registration agreement terms, records, abuse duties and termination grounds (ICANN, Registries & Registrars).
RDAP: the Registration Data Access Protocol, HTTP and JSON lookups of registration data found through IANA bootstrap files, which replaced WHOIS as the definitive source for gTLD data (Registration Data & RDAP).
RDAP bootstrap: IANA's JSON registries pairing TLDs, IP prefixes and AS ranges with base RDAP URLs, matched right to left with the longest match winning (Registration Data & RDAP).
RDDS: registration data directory services: RDAP, and WHOIS where it still runs, which must publish the domain, registrar, abuse contacts, statuses, dates and nameservers (Registration Data & RDAP).
Redacted member: the RFC 9537 RDAP extension that lists each redacted field with its name, a JSONPath to it and the redaction method (Registration Data & RDAP).
Redemption Grace Period: the period after a registrar deletes a name outside the Add Grace Period, during which only the registrar can restore it (The Domain Lifecycle).
Registrar lock: clientTransferProhibited, usually with update and delete prohibitions, set by the registrar and removable by the account holder; it stops accidental transfers but not anyone who can log in (Transfers, Locks & Registrar Security).
Registration agreement: the contract between the registrar and its registrant, which must carry the terms the RAA and the registry require (ICANN, Registries & Registrars).
Registration Data Policy: the consensus policy governing what registrars collect, transfer to registries, publish and redact, disclose on request and retain (Registration Data & RDAP).
Registration Data Request Service (RDRS): ICANN's voluntary request router that passes disclosure requests to registrars that take part, deciding nothing and holding no data (Registration Data & RDAP).
Registry agreement: the contract between ICANN and a registry operator, requiring every registration to go through an ICANN-accredited registrar with non-discriminatory access (ICANN, Registries & Registrars).
Registry fee: the registry's wholesale price per name-year, paid by the registrar from its payment security at the transaction (ICANN, Registries & Registrars).
Registry lock: the serverTransferProhibited, serverUpdateProhibited and serverDeleteProhibited statuses set by the registry, released only after an out-of-band check, which protect against a compromised registrar account (Transfers, Locks & Registrar Security).
Registry Registrar Protocol (RRP): EPP's predecessor, a text protocol for the thin .com registry (ICANN, Registries & Registrars).
Registry service provider (RSP): the company that operates a TLD's technical back end for the brand on the contract, a separate business from the registry (New gTLDs & ccTLDs).
Registry-Registrar Agreement (RRA): the contract between a registry and each registrar covering the protocol, billing and the payment security that sets the registrar's credit (ICANN, Registries & Registrars).
Renew/Extend Grace Period: the days after an explicit renewal during which a registrar delete credits the renewal fee (The Domain Lifecycle).
Reseller (registrar): a seller of domain names under a wholesale registrar's accreditation, who pays no ICANN fees while the registrar answers to ICANN for it (ICANN, Registries & Registrars).
Restore: recovering a name from redemption in two EPP steps, a restore request and then a restore report with the registration data before and after (The Domain Lifecycle).
Result codes (EPP): four-digit EPP response codes whose first digit is success (1) or failure (2), which a registrar's code must branch on rather than on messages (The Domain Data Model & EPP).
Routing policies: DNS answer strategies such as simple, weighted, latency, geolocation, geoproximity, IP-based, failover and multivalue, priced as premium query types (DNS Hosting & DNSSEC).
SAC115: the Security and Stability Advisory Committee report proposing an interoperable approach to abuse handling, whose definition of DNS Abuse the contracts adopted (DNS Abuse at the Registrar).
SC-085v2: the CA/Browser Forum ballot requiring CAs to validate DNSSEC, when present, for CAA and domain validation lookups, so a broken signed zone fails certificate issuance (DNS Hosting & DNSSEC).
Sessions (EPP): EPP over TCP port 700 with TLS and mutual authentication, the registrar presenting a client certificate, under per-registry session limits (The Domain Data Model & EPP).
Signed Mark Data (SMD): the file from the Trademark Clearinghouse that a trademark holder needs to register during sunrise (New gTLDs & ccTLDs).
SOA record: the record at a zone's apex naming the primary server, contact, serial and the refresh, retry, expire and minimum timers (DNS Hosting & DNSSEC).
Sunrise: the launch phase restricted to trademark holders with a Signed Mark Data file, before general registration opens (New gTLDs & ccTLDs).
TDRP (Transfer Dispute Resolution Policy): the dispute policy for transfers, which only the gaining or losing registrar can file, with remedies that approve or reverse the transfer (Domain Disputes).
Temporary Specification: the ICANN Board's 2018 interim rule that redacted personal data from public registration data for the GDPR, later replaced by policy from the EPDP (Registration Data & RDAP).
Transaction identifiers (EPP): the client's <clTRID> and the server's <svTRID>, which together identify an EPP transaction and should both be logged and retained (The Domain Data Model & EPP).
Transfer Authorization Code (TAC): the Transfer Policy Review's name for the auth code: generated only on request, one-time use, valid for a fixed life and announced to the registrant when issued (Transfers, Locks & Registrar Security).
Transfer Grace Period: the days after a completed transfer during which a registrar delete credits the transfer fee (The Domain Lifecycle).
Transfer Pending Period: the days after a transfer request during which the losing registrar may approve or deny; if it does neither, the registry approves automatically (The Domain Lifecycle).
Transfer Policy: ICANN's consensus policy for inter-registrar transfers and changes of registrant, which gives registrants portability under fixed notice and approval clocks (Transfers, Locks & Registrar Security).
Transfer Policy Review: the GNSO review whose recommendations, adopted by ICANN's Board, rename and tighten the auth code, drop the gaining FOA and rename the losing FOA a Transfer Confirmation (Transfers, Locks & Registrar Security).
TTL: the time a resolver may cache a DNS record; a short TTL makes changes and failover fast and costs more queries (DNS Hosting & DNSSEC).
UDRP: ICANN's Uniform Domain-Name Dispute-Resolution Policy, a mandatory administrative proceeding in which a trademark owner can win cancellation or transfer of a name, nothing else (Domain Disputes).
UDRP elements: the three things a complainant must prove: the name is identical or confusingly similar to its mark, the registrant has no rights or legitimate interests, and the name was registered and used in bad faith (Domain Disputes).
UDRP freeze: the bar on transferring a disputed name to another holder or registrar while a UDRP is pending and for a period after it concludes (Domain Disputes).
UDRP providers: the approved dispute providers (ADNDRC, CIIDRC, the Czech Arbitration Court, Forum and WIPO) with which UDRP complaints are filed (Domain Disputes).
UDRP wait: the ten business days a registrar waits after a decision ordering transfer or cancellation, implementing it unless the registrant shows a file-stamped court complaint (Domain Disputes).
URS: the Uniform Rapid Suspension System, a faster, cheaper route for clear-cut infringement in new gTLDs, decided on clear and convincing evidence, with suspension as the only remedy (Domain Disputes).
URS remedy: the registry suspending the name for the rest of its registration period and pointing its nameservers at the provider's informational page (Domain Disputes).
WHOIS: the original public directory of registration data over TCP port 43, whose contractual obligation for gTLDs ended when RDAP became the definitive source (Registration Data & RDAP).
Zone (DNS): a contiguous part of the DNS namespace served from one set of name servers, with a single SOA and NS records at its apex (DNS Hosting & DNSSEC).