Domain & DNS terms, explained simply

A plain-English A–Z glossary of every domain name and DNS term you're likely to encounter, from A record to WHOIS.

Domain names and DNS come with a lot of technical vocabulary. This glossary explains every common term in plain English — no jargon required.

Quick summary

Use this glossary whenever you encounter an unfamiliar term in a guide, email, or conversation about your domain. Terms are listed A–Z. Click any term in the cross-links throughout the help center to come back here.

A

A record A DNS record that maps a domain name to an IPv4 address. This is how your domain finds your website's server. For example, yourbusiness.com → 185.199.108.153. See DNS records explained.

AAAA record Like an A record, but for IPv6 addresses — the newer, longer address format. Most hosting providers manage these automatically.

Apex domain The root domain without any prefix. yourbusiness.com is the apex domain; www.yourbusiness.com is not. Also called "root domain" or "bare domain."

Auth code See EPP code.

Auto-renew A setting at your registrar that automatically renews your domain before it expires, charging your payment method on file. See Turning on auto-renew.

Authoritative nameserver The nameserver that holds the official, definitive DNS records for a domain. When a DNS lookup is performed, the authoritative nameserver provides the final answer.

B

Bare domain See apex domain.

C

CAA record (Certificate Authority Authorization) A DNS record that specifies which certificate authorities are allowed to issue SSL certificates for your domain. Adds a layer of security against fraudulent certificates.

CNAME record (Canonical Name) A DNS record that maps one domain name to another domain name (rather than to an IP address). Used for aliases and for connecting third-party services. See DNS records explained.

D

DKIM (DomainKeys Identified Mail) An email authentication method that adds a cryptographic signature to outgoing emails, proving they're genuine and haven't been tampered with. Stored as a TXT record in DNS. See DKIM records, explained.

DMARC (Domain-based Message Authentication, Reporting & Conformance) A DNS policy record that tells receiving email servers what to do when SPF or DKIM checks fail. Options are none, quarantine, or reject. Also provides email abuse reports. See DMARC records, explained.

DNS (Domain Name System) The global system that translates human-readable domain names (like yourbusiness.com) into numeric IP addresses that computers use to communicate. Often described as "the internet's phone book." See What is DNS?.

DNS propagation The process by which a DNS change spreads to DNS servers around the world. Takes a few minutes to 48 hours, depending on TTL settings. See DNS propagation: why changes take time.

DNS record An individual instruction stored in DNS that tells the internet something about your domain — where your website lives, who handles your email, etc. Common types include A, CNAME, MX, and TXT. See DNS records explained.

DNS resolver A server run by your internet provider (or a public service like Google 8.8.8.8 or Cloudflare 1.1.1.1) that performs DNS lookups on your behalf when you visit a website.

Domain expiry The date on which your domain registration ends. If not renewed, the domain passes through a grace period, then a redemption period, and eventually becomes available for others to register. See What happens when a domain expires.

Domain lock See transfer lock.

Domain name The human-readable address of a website, like yourbusiness.com. Registered at a domain registrar on a yearly basis. See What is a domain name?.

Domain privacy A service that replaces the registrant's personal details in the public WHOIS database with those of a privacy proxy. Also called WHOIS privacy or private registration. See Domain privacy protection explained.

Domain registrar A company accredited by ICANN to sell and manage domain name registrations. Examples include GoDaddy, Namecheap, Cloudflare Registrar, and Hover.

Domain transfer Moving a domain from one registrar to another. Requires unlocking the domain and obtaining an EPP/auth code. See How to transfer a domain.

E

EPP code (Extensible Provisioning Protocol code) A password-like code required to authorize a domain transfer to a new registrar. Also called auth code, authorization code, or transfer code. See Unlocking a domain & getting the auth code.

Extension See TLD.

G

Grace period The period immediately after a domain expires during which it can still be renewed at the normal price (typically around 30 days). After this, a higher redemption fee applies. See What happens when a domain expires.

H

Host / Hostname In DNS context, the "name" part of a record — the part before your domain. @ represents the root domain. www is the hostname for www.yourbusiness.com. mail is the hostname for mail.yourbusiness.com.

I

ICANN (Internet Corporation for Assigned Names and Numbers) The non-profit organization that coordinates the global internet's naming systems, including domain name registration policies and the root DNS zone. All registrars are accredited by ICANN.

IP address A numerical label assigned to each device connected to the internet. IPv4 addresses look like 185.199.108.153. Your DNS A record maps your domain name to your server's IP address.

M

MX record (Mail Exchange) A DNS record that specifies which mail server handles incoming email for a domain. Has a priority number — lower numbers have higher priority. See Email DNS records.

N

Nameserver A server that holds the authoritative DNS records for a domain. When DNS looks up your domain, it queries your nameservers. Set at your domain registrar. See Nameservers vs DNS records.

NS record (Nameserver record) A DNS record that specifies which nameservers are authoritative for a domain. These are set at your registrar and point to your DNS provider.

NXDOMAIN A DNS response meaning "non-existent domain." You see this when a domain doesn't exist or its DNS is misconfigured. Often shown as "Server not found" in browsers.

P

Parked domain A domain that is registered but not currently hosting an active website. May show a blank page, a registrar's ad page, or a placeholder. See Parked & redirected domains.

Propagation See DNS propagation.

R

Registrant The person or organization listed as the legal owner of a domain. Registrant details are stored in WHOIS. Should always be the business owner, not a developer or agency. See Who owns your domain.

Registrar See domain registrar.

Registry The organization that manages a top-level domain (TLD). For example, Verisign manages .com. Registries set policies and pricing; registrars sell registrations to the public.

Redemption period The period after a domain's grace period expires (approximately 30–60 days after expiry) during which the domain can still be recovered, but at a much higher redemption fee. See What happens when a domain expires.

Redirect Automatically sending visitors from one URL to another. A 301 redirect is permanent; a 302 is temporary. See Parked & redirected domains.

Root domain See apex domain.

S

SOA record (Start of Authority) An internal DNS record automatically created by your DNS provider. It contains information about the zone and is managed automatically — you don't need to edit it.

SPF (Sender Policy Framework) An email authentication DNS record (TXT type) that lists the mail servers authorized to send email from your domain. Helps prevent spoofing and improves email deliverability. See SPF records, explained.

SRV record (Service record) A DNS record used for specific services that need special routing, such as VoIP, some Microsoft 365 features, and SIP. Specifies the hostname and port number for the service.

SSL certificate A digital certificate that enables HTTPS (encrypted) connections to your website. Most hosting providers issue SSL certificates automatically. Related to DNS in that the domain must point to your server before SSL can be issued. See What is SSL & HTTPS?.

Subdomain A prefix added to a domain name to create a separate address. blog.yourbusiness.com and shop.yourbusiness.com are subdomains. See Subdomains explained.

T

TLD (Top-Level Domain) The last part of a domain name — .com, .net, .org, .co.uk, etc. Also called the "extension." Managed by registries.

Transfer lock A security feature at registrars that prevents a domain from being transferred without authorization. Must be disabled before initiating a transfer. See Unlocking a domain & getting the auth code.

TTL (Time To Live) A number (in seconds) that specifies how long DNS servers should cache a record before fetching a fresh copy. Lower TTL = changes spread faster. Higher TTL = fewer DNS queries and better performance. 3600 (1 hour) is a common default.

TXT record A DNS record that holds arbitrary text information. Used for domain verification, SPF, DKIM, DMARC, and other purposes. See DNS records explained.

U

UDRP (Uniform Domain-Name Dispute-Resolution Policy) An ICANN-administered process for resolving disputes over domain names, particularly when a domain infringes on a trademark. Allows trademark owners to potentially recover a domain from a squatter.

W

WHOIS A public database containing registration information for domain names — including the registrant's name, address, email, and expiry date. Look up any domain at lookup.icann.org. See Domain privacy protection explained.

WHOIS privacy See domain privacy.

Wildcard DNS A DNS record that matches any subdomain. For example, *.yourbusiness.com would match anything.yourbusiness.com. Useful for wildcard SSL certificates that cover all subdomains.

Z

Zone file A text file containing all the DNS records for a domain. Many DNS providers let you export or import zone files. Useful for backing up your DNS before migrations.

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Domain & DNS terms, explained simply

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