Glossary

Short, practical definitions of the terms used on this site, in the specific sense this proposal uses them. They are simplified for accessibility, not normative.

DNS (Domain Name System): The global system that translates domain names like example.com into the technical information needed to reach them, primarily the addresses of servers.
TLD (top-level domain): The last label of a domain name: com, org, ai. Each TLD is operated by a registry.
gTLD / ccTLD: Generic top-level domains (com, org, and the newer extensions) operate under contracts with ICANN. Country-code top-level domains (us, de, ai) are administered under the policies of the country or territory they are designated to.
Registry: The organization that operates a TLD: maintains its authoritative database and publishes its zone file.
Registrar: A company accredited to sell domain registrations to the public and submit them to the registry. Registrars are not directly involved in this proposal.
Registrant: The person or organization that registers a domain name. Registrant identity and contact details are not part of zone files and are not part of this proposal.
Zone: The portion of the DNS namespace a registry is authoritative for; for a TLD registry, essentially the TLD and its delegations.
Zone file: The published snapshot of a zone's DNS data: which domains exist and which nameservers they delegate to, along with related technical records. It contains no registrant names, emails, or addresses.
CZDS (Centralized Zone Data Service): ICANN's portal through which vetted, approved users request and download gTLD zone files, currently as full daily snapshots.
ICANN: The Internet Corporation for Assigned Names and Numbers, the nonprofit that coordinates the DNS through a multistakeholder policy community.
GNSO / BC: The Generic Names Supporting Organization, ICANN's policy body for gTLDs; the Business Constituency is the GNSO stakeholder group representing business users of the internet, through which this proposal is brought.
Resource record (RR): A single DNS data entry: an owner name, a type, a time-to-live, and a value. One line of a zone file.
RRset (Resource Record set): All resource records sharing the same owner name and type, treated as one unit. If a domain lists four nameservers, those four NS records form one RRset. DNS validates and DNSSEC signs at the RRset level, which is why this proposal's change events operate on RRsets.
Owner name: The domain name a resource record belongs to; the left-hand side of a zone file line.
TTL (time to live): How long, in seconds, a record may be cached before being looked up again. Records in one RRset share a TTL.
Delegation: The pointer from a TLD zone to the nameservers responsible for a domain, expressed as the domain's NS RRset. A domain "exists" in a zone file when it is delegated.
NS record: Names a nameserver responsible for a domain. The core content of a TLD zone file.
Glue record: The IP address of a nameserver, published in the TLD zone when the nameserver's name lives inside the domain it serves, breaking a circular lookup.
DNSSEC / DS record: DNSSEC adds cryptographic signatures to DNS data. The DS record in the TLD zone anchors a domain's keys and changes when the registrant rolls keys; it reflects a real registrant-driven event, so it is in scope for deltas.
RRSIG / NSEC / NSEC3: DNSSEC's signature and denial-of-existence records. They are regenerated automatically each time a zone is re-signed, without any underlying change, so this proposal excludes them from deltas by default.
Snapshot: One full published copy of a zone file at a point in time; currently daily.
Delta (differential): The set of changes between two consecutive snapshots: what was added, removed, or modified, instead of the entire file.
Baseline / sequence: A baseline is a known-good full snapshot a consumer starts from; sequence numbers order the deltas that follow it, so a consumer can detect a missed delta and recover.
Canonicalization: The deterministic normalization rules (ordering, case, which record types count) applied before computing a delta, so that any two parties comparing the same snapshots derive the identical change set.
RDAP / WHOIS: The protocols for looking up registration data about a domain, including registrant information where policy permits. Deliberately out of scope: this proposal concerns zone data only.