As of: 18 October 2026

Translated from German. In case of discrepancies, the German version applies.

Glossary Domains and DNS

Domain names, registries, transfers and name resolution.

Matching task: Moving a domain · All topics in the glossary

Terms

A and AAAA records

Also: A-Record, AAAA-Record

DNS records that map a name to an IPv4 address (A) or an IPv6 address (AAAA). They determine on which server the website is accessed.¹

Related: DNS, IP address, CNAME record · More on this

Anycast

A mode of operation in which the same IP address of a service can be reached at several independent locations; data packets arrive at one of these locations (RFC 4786). It is common for root servers and large DNS services, because queries are answered nearby and the failure of one location does not affect the whole service.²

AuthInfo

Also: authcode, auth code, transfer code

One-time password with which the domain holder authorises the move to another registrar. For .de domains it expires after 30 days, according to DENIC. For generic endings, the registrar must hand it over under ICANN rules and may not refuse to do so solely because of a dispute over payment; it may deny the transfer itself if a previous or the current registration period has not been paid.³,⁴

Related: Domain transfer, DENIC, ICANN · More on this

CAA record

Also: Certification Authority Authorization

A DNS record with which the domain holder specifies which certificate authorities may issue certificates for the domain (RFC 8659). A certificate authority must look for it before issuing. If a CAA record exists, the authority may in principle only issue if it is listed there; if there is none, CAA does not restrict anything. Anyone who sets a CAA record must therefore include every certificate provider they use.⁵

CNAME record

Also: alias record

DNS record that makes one name an alias pointing to another name, such as www pointing to the main domain or to an external service. There must be no other records for the same name alongside a CNAME.⁶

Related: A and AAAA records, DNS

Country-code ending (ccTLD)

Also: ccTLD, Country Code Top-Level Domain

Two-letter ending assigned to a country or territory, such as .de or .at. For each country-code ending, the responsible registry sets its own rules, for example for changing provider.⁷

DENIC

Also: DENIC eG

The registry for .de domains (Germany). For changing the provider of a .de domain, DENIC uses the AuthInfo procedure.³

DNS

Also: Domain Name System, name resolution

The worldwide distributed directory that translates domain names into addresses and other information, such as where emails are delivered. It is based on the standards RFC 1034 and RFC 1035 from 1987.⁶,¹

DNS over HTTPS and DNS over TLS

Also: DoH, DoT, Encrypted DNS

Methods that encrypt DNS queries between a device and the resolver: DoH sends them over HTTPS (RFC 8484), DoT over a TLS connection on port 853 (RFC 7858). They protect confidentiality in transit; the authenticity of DNS data, on the other hand, is secured by DNSSEC.⁸,⁹,¹⁰

DNS propagation

Also: Propagation

Colloquially, the waiting time until a DNS change is visible everywhere. Nothing is actually distributed: resolvers keep cached answers until their TTL has expired and only then ask again. Lowering the TTL some time before a change shortens this phase.¹,¹¹

DNS zone

Also: Zone, Zone file

A section of the name space for which the same name servers are responsible, such as example.de with all records that have not been handed over to separate name servers of a subdomain. A zone can be described completely as a set of DNS records (RFC 1034) and is often kept as a zone file by the DNS provider.⁶

Related: DNS, Name server, SOA record, Subdomain

DNSSEC

Also: DNS Security Extensions

Extension of the DNS in which records are digitally signed so that recipients can detect forgeries. DNSSEC protects the authenticity of the answers but does not encrypt them.¹⁰

Domain

Also: domain name

A readable name on the internet such as hosting-stammtisch.de that points to servers via the DNS. A domain is not bought but registered for a term and has to be renewed.⁶,¹²

Domain status

Also: EPP status code, Transfer lock, clientTransferProhibited

Flags in the registration data that record what is currently possible with a domain. The clientTransferProhibited lock, for example, makes the registry reject any transfer to another registrar and thus helps prevent domain theft. If the domain is to move, the current registrar must, according to ICANN, first remove this lock.¹³

Domain transfer

Also: change of provider, KK-Antrag (German, outdated)

Moving a domain from one registrar to another without the holder changing. This is separate from a change of holder and from switching the DNS.³,⁴

EPP (Extensible Provisioning Protocol)

Also: Extensible Provisioning Protocol

The standard protocol through which registrars create, modify, renew, transfer and delete domains at a registry. It is described as Internet Standard STD 69 in RFC 5730. Domain holders usually only see its status codes and the auth code.¹⁴

Generic ending (gTLD)

Also: gTLD, Generic Top-Level Domain

Endings without reference to a country, such as .com, .net, .org or newer ones such as .shop. For changing between registrars, ICANN's Transfer Policy applies here.⁴,⁷

Glue record

Also: Glue

An address record of a name server that is also stored in the parent zone. It is needed when the name server lies below the domain for which it is responsible (such as ns1.example.de for example.de): without glue, one would have to ask exactly the server one is trying to find for its address (RFC 1034, quoted in RFC 9499).¹¹,¹⁵

ICANN

Also: Internet Corporation for Assigned Names and Numbers

Non-profit organisation that, among other things, sets rules for generic endings and accredits registrars for these endings – for example the Transfer Policy for changing registrar.⁴

Internationalised domain name (IDN)

Also: umlaut domain, Punycode

A domain with characters outside a–z, 0–9 and the hyphen, for example with umlauts. Technically it is converted into an ASCII form with the prefix xn--; the prefix is defined by IDNA (RFC 5890), and the conversion procedure is called Punycode (RFC 3492).¹⁶,¹⁷

Related: Domain

MX record

Also: Mail Exchanger

DNS record that specifies which servers accept emails for a domain. If it is switched too early or incorrectly during a move, messages end up in an empty mailbox or do not arrive at all.¹

Related: DNS, SPF · More on this

Name server

Also: DNS server

Servers that authoritatively hold a domain's DNS records. Which name servers are responsible is stored at the registry. If they are with a third party, changing host initially changes nothing in the DNS.⁶

Related: DNS, Registry, Glue record, DNS zone · More on this

PTR record

Also: Reverse DNS, rDNS

A record for the reverse direction of name resolution: it assigns a name to an IP address, for IPv4 via the special domain in-addr.arpa (RFC 1035). It is maintained by whoever owns the address range, which in web hosting is usually the host and not the domain holder.¹

RDAP and WHOIS

Also: WHOIS, Registration Data Access Protocol

Lookup services for a domain's registration data, such as registrar, status and expiry date. According to its specification (RFC 7480), RDAP is the successor to WHOIS and returns answers in JSON format (RFC 9083); according to ICANN, registries and registrars for generic endings must offer RDAP. Holder details of private individuals are often not public: for .de, DENIC does not show them for data protection reasons.¹⁸,¹⁹,²⁰,²¹

Related: Registrar, Registry · More on this

Redemption Grace Period (RGP)

Also: RGP

A period after a domain has been deleted during which it can still be recovered. For generic top-level domains (gTLDs), ICANN requires 30 days (sponsored TLDs excepted). For .de, too, deletion is followed by a 30-day RGP; according to DENIC, during this time only the last domain holder or a third party named by them can register the domain again.²²,²³,²⁴

Registrar

Also: domain provider

Company through which you have domains registered, renewed and changed at the registry. The host is often also the registrar, but this is not mandatory.

Registry

Also: Registry, registration authority

Organisation that maintains the central database of an ending and runs its name servers, for .de for example DENIC. Domain holders usually do not deal with it directly but with a registrar.⁷

Resolver

Also: Recursive resolver, DNS resolver

A DNS server that accepts queries from devices, obtains the answer from the responsible name servers and usually caches it (RFC 9499). It is typically run by the internet provider, the company network or a public service. Because it keeps answers until the TTL expires, DNS changes do not arrive everywhere at once.¹¹,¹

Root server

Also: Root zone

The name servers of the DNS root zone; they point to the name servers of the individual top-level domains and are thus the starting point of every name resolution. According to IANA, 13 named authorities are listed in the root zone (a.root-servers.net to m.root-servers.net), behind which stands a network of hundreds of servers in many countries.²⁵,¹¹

SOA record

Also: Start of Authority

A record that marks the start of a DNS zone and contains administrative details: the primary name server, the mailbox of the person responsible, a serial number and timing values according to which other name servers synchronise their copy of the zone (RFC 1035).¹

Subdomain

Also: Third-level domain

A name below a domain, such as shop.example.de under example.de; technically, www is also a subdomain. RFC 1034 calls a domain a subdomain of another if it is contained within it. The domain holder sets up subdomains in the DNS themselves; no separate registration is needed.⁶

Related: Domain, DNS zone, CNAME record · More on this

Top-level domain (TLD)

Also: domain ending

The last part of a domain name, such as .de, .com or .berlin. Which endings exist and who manages them is listed by IANA in the Root Zone Database.⁷

TTL (time to live)

Also: validity period

A value in seconds stating how long a DNS record may be cached by other servers. Lowering the TTL before a move ensures that changes reach everywhere faster.¹

Related: DNS, DNS propagation, Resolver · More on this

TXT record

Also: TXT-Record

DNS record for free-form text. Today mainly used for email sender rules (SPF, DMARC, DKIM keys) and for proof of ownership towards services such as search engines.¹

Related: SPF, DKIM, DMARC, Search Console · More on this