Domain Name Glossary: Every Term You Need to Know
Domain names come with their own vocabulary — technical terms, industry jargon, and acronyms that can be confusing for newcomers and occasionally even for experienced website owners. This glossary provides clear, concise definitions for every significant term in the domain name world, organised alphabetically for easy reference.
A
A Record — A DNS record type that maps a domain name to an IPv4 address. The most fundamental DNS record, used to point a domain to a web server. Example: top1hosting.com/ → 104.21.96.42.
AAAA Record — A DNS record type that maps a domain name to an IPv6 address. The IPv6 equivalent of an A record.
Accreditation — The process by which registrars are approved by ICANN to sell domain registrations. Only ICANN-accredited registrars can register gTLD domains.
Aftermarket — The secondary market for domain names, where already-registered domains are bought and sold. Distinct from new registrations with a registrar.
Aged Domain — A domain name that has been registered for a significant period, often marketed for its potential SEO value from an established backlink profile. See our guide on Aged Domains.
Anycast — A routing technique that assigns the same IP address to multiple servers in different geographic locations. Used by root name servers and major DNS providers to distribute query load globally and improve redundancy.
Auth Code — See EPP Code.
Authoritative Name Server — The DNS server that holds the definitive DNS records for a specific domain. When a resolver queries for yourdomain.com, the authoritative name server provides the final, authoritative answer.
B
Backorder — A service that attempts to register a specific domain name the moment it becomes available (expires and drops). See our guide on Domain Backorders.
Brand TLD — A top-level domain operated exclusively by a brand (e.g., .google, .apple, .bmw). Not available for public registration.
C
CAA Record — Certification Authority Authorisation record. Specifies which Certificate Authorities may issue SSL/TLS certificates for a domain.
ccTLD — Country Code Top-Level Domain. A two-letter TLD assigned to a specific country or territory (e.g., .nl for Netherlands, .de for Germany). See our guide on ccTLDs Explained.
CNAME Record — Canonical Name record. A DNS record type that creates an alias from one domain name to another domain name rather than directly to an IP address.
Cybersquatting — The bad-faith registration of a domain name containing another party’s trademark, with intent to profit from that trademark’s goodwill. See our guide on Cybersquatting.
D
DNS (Domain Name System) — The global distributed database system that translates human-readable domain names into machine-readable IP addresses. The “phone book of the internet.”
DNS Propagation — The process by which DNS record changes spread across the global network of resolvers and caches. Can take minutes to 48 hours depending on TTL values.
DNSSEC — DNS Security Extensions. A suite of specifications that adds cryptographic signatures to DNS records, protecting against spoofing and cache poisoning. See our guide on DNSSEC.
Domain Lock — Also called Registrar Lock or Transfer Lock. A domain status that prevents the domain from being transferred to another registrar without explicit authorisation. Shown as clientTransferProhibited in WHOIS.
Domain Name — A human-readable address used to identify a website on the internet, mapped to an IP address through the DNS system. Consists of a second-level domain and a top-level domain (e.g., top1hosting.com/).
Domain Privacy — A service that replaces the registrant’s personal contact information in the public WHOIS record with proxy information. Also called WHOIS Privacy or Privacy Guard.
Drop — The moment a domain name that has been through the full expiry process is deleted from the registry and becomes available for re-registration. Also called the domain drop.
Drop Catching — The practice of attempting to register a domain name the instant it is released (dropped) from the registry after expiry.
DS Record — Delegation Signer record. A DNSSEC record published in the parent zone (TLD) that contains a hash of the domain’s key-signing key, establishing the chain of trust.
E
EMD (Exact Match Domain) — A domain name that exactly matches a search query (e.g., bestcarinsurance.com for “best car insurance”). See our guide on Exact Match Domains.
EPP Code — Extensible Provisioning Protocol code. Also called auth code, authorisation code, or transfer key. A secret code required to authorise a domain transfer to another registrar.
Escrow — A neutral third-party service that holds payment during a domain transaction, releasing funds to the seller only after the buyer has confirmed receipt of the domain. Escrow.com is the standard service for domain transactions.
Expired Domain — A domain whose registration period has lapsed and that has not been renewed. May be available through auction or the public drop process. See our guide on Expired Domains.
F
FQDN (Fully Qualified Domain Name) — The complete domain name specifying its exact location in the DNS hierarchy, including all levels from the subdomain to the root. Example: www.top1hosting.com.
G
Grace Period — The period immediately after a domain expires during which the original registrant can still renew at standard price (typically 0–30 days).
gTLD (Generic Top-Level Domain) — A top-level domain not associated with any specific country. Includes original gTLDs (.com, .net, .org) and new gTLDs (.shop, .tech, .agency, etc.).
H
Hreflang — An HTML attribute specifying the language and geographic target of a web page. Used with international websites to tell search engines which language and country version to show to which users.
HOSTS.TXT — The precursor to DNS. A single text file maintained at SRI that mapped hostnames to IP addresses on ARPANET. Replaced by DNS in 1983 due to scalability limitations.
I
IANA (Internet Assigned Numbers Authority) — The ICANN function responsible for coordinating the global pool of IP addresses, ASNs, protocol parameters, and the DNS root zone.
ICANN — Internet Corporation for Assigned Names and Numbers. The non-profit organisation that coordinates the domain name system, IP address allocation, and internet protocol parameters globally. See our guide on ICANN Explained.
IDN (Internationalized Domain Name) — A domain name containing characters outside the standard ASCII set — Arabic, Chinese, Cyrillic, accented Latin characters, and others. Encoded using Punycode for DNS compatibility.
IP Address — Internet Protocol address. A numerical label identifying a device on a network. IPv4 addresses are 32-bit numbers (e.g., 192.168.1.1); IPv6 addresses are 128-bit (e.g., 2001:0db8::1). Domain names map to IP addresses through DNS.
M
MX Record — Mail Exchange record. A DNS record specifying which mail servers receive email for a domain, with priority values determining delivery order.
N
Nameserver (NS) — A server that holds DNS records for a domain zone. Nameservers are specified in NS records and at the registrar level; changing nameservers delegates DNS management to a different provider.
New gTLD — A generic top-level domain approved by ICANN after 2013 under the New gTLD Program. Includes industry-specific (.shop, .law), geographic (.amsterdam, .london), and brand (.google, .apple) extensions. See our guide on New gTLDs.
P
Parking — The practice of placing a registered but undeveloped domain on a placeholder page, typically displaying PPC advertisements. See our guide on Domain Parking.
Premium Domain — A domain name priced above standard registration rate, either by the registry (registry premium) or by an owner selling on the aftermarket. See our guide on Premium Domains.
PTR Record — Pointer record. Used for reverse DNS lookups, mapping an IP address back to a hostname.
Punycode — An encoding system that converts internationalized domain names (containing non-ASCII characters) into ASCII-compatible strings using the xn-- prefix. Used for DNS compatibility.
R
RDAP (Registration Data Access Protocol) — The modern, structured replacement for WHOIS. Provides machine-readable domain registration data with support for differentiated access levels.
Redemption Period — The period after a domain’s grace period expires during which the original registrant can recover the domain at a premium fee (typically $80–$200+ above standard renewal). Generally lasts 30 days.
Registrant — The individual or organisation that registers and holds the rights to a domain name. The domain owner.
Registrar — An ICANN-accredited company authorised to register domain names and manage the registrant relationship. The retail layer of the domain market (e.g., Namecheap, GoDaddy, CloudFlare Registrar). See our guide on Registrar vs. Registry.
Registry — The organisation that maintains the authoritative database for a specific TLD (e.g., Verisign for .com, SIDN for .nl). The wholesale layer of the domain market.
Registry Lock — A stronger form of domain lock applied at the registry level (not just the registrar level), requiring out-of-band verification for any domain changes. Used for critical business domains requiring maximum security.
Resolver (DNS Resolver) — A DNS server (typically operated by an ISP or public DNS service) that receives DNS queries from clients and performs the recursive lookup process to find the authoritative answer.
Root Name Server — One of the 13 DNS server addresses (A through M) at the top of the DNS hierarchy. They hold the root zone — the master list of all TLDs and their authoritative name servers. See our guide on Root Name Servers.
S
Second-Level Domain (SLD) — The portion of a domain name immediately to the left of the TLD. In top1hosting.com/, "top1hosting" is the second-level domain — the part you register.
SIDN — Stichting Internet Domeinregistratie Nederland. The registry operator for the .nl ccTLD. See our guide on SIDN Explained.
SPF Record — Sender Policy Framework record. A TXT record that specifies which mail servers are authorised to send email on behalf of a domain. An email authentication protocol.
Subdomain — A prefix added to the left of a domain name (e.g., blog.yourdomain.com). Created via DNS records; no additional registration required. See our guide on Subdomains Explained.
T
TLD (Top-Level Domain) — The rightmost part of a domain name, after the final dot. Includes gTLDs (.com, .net, .org), ccTLDs (.nl, .de, .uk), and new gTLDs (.shop, .tech). Also called the domain extension.
TMCH (Trademark Clearinghouse) — An ICANN-operated database of verified trademarks. Provides trademark holders with sunrise registration rights and notification services during new gTLD launches.
TTL (Time to Live) — A value in DNS records (measured in seconds) specifying how long a resolver should cache the record before checking again. Determines how quickly DNS changes propagate globally.
TXT Record — Text record. A DNS record containing free-form text data, used for domain verification, email authentication (SPF, DKIM, DMARC), and other purposes.
Transfer — The process of moving a domain registration from one registrar to another. Requires an EPP/auth code and the domain to be unlocked. Regulated by ICANN’s transfer policy.
Typosquatting — Registering domain names that are common misspellings or typographical variations of well-known brand domains, with intent to capture misdirected traffic.
U
UDRP (Uniform Domain Name Dispute Resolution Policy) — ICANN’s mandatory dispute resolution policy for bad-faith domain registration cases. Provides a fast, relatively affordable alternative to litigation for trademark holders. See our guide on UDRP Explained.
URL (Uniform Resource Locator) — The complete web address of a specific resource, including protocol, domain name, and path. A domain name is one component of a URL. See our guide on Domain Name vs. URL.
W
WHOIS — A protocol and database that stores registration information for domain names. Post-GDPR, most personal data in WHOIS is redacted for public queries. See our guide on WHOIS and Domain Privacy.
Wildcard Subdomain — A DNS record using an asterisk (*) as the name, matching any subdomain not explicitly defined. Example: *.yourdomain.com resolving to a specific IP means any subdomain (anything.yourdomain.com) resolves to that address.
Z
Zone File — The file containing all DNS records for a domain, stored on the authoritative name server. Defines A records, MX records, CNAME records, and all other DNS configuration for the domain.
Zone Transfer — The process of copying a zone file from a primary name server to a secondary name server. Used for redundancy and load distribution across multiple authoritative name servers.