Domains & DNS: terms A to Z

Domains and DNS have a lot of unfamiliar vocabulary. This page is your reference. You don't need to memorize it. Just know it's here when someone says "update your CNAME" and you want to know what that means.

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A to C

Term	Plain-English definition
A record	The DNS record that points your domain name to a specific IP address (server). "A" stands for Address.
AAAA record	Like an A record, but for IPv6 addresses: the newer, longer format of IP addresses.
Accreditation	The process that authorizes a company to sell domain names. To sell generic extensions like .com, a registrar has to be accredited by ICANN; for a country-code extension such as .uk, accreditation comes from that country's registry instead.
Auth code	Also called EPP code, transfer code, or authorization code. A password-like string needed to transfer a domain to a new registrar.
Auto-renew	A setting at your registrar that renews your domain before it expires, charging the payment method you have on file. Always keep this on.
Cloudflare	A popular service that acts as a DNS provider, CDN, and security layer for websites. See Cloudflare basics for clients.
CNAME record	Canonical Name record. Points one domain name (or subdomain) to another domain name instead of an IP address. Often used for www or subdomains like mail.yoursite.com.

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D to G

Term	Plain-English definition
DKIM	DomainKeys Identified Mail. A cryptographic signature added to emails sent from your domain; receiving servers use a public key published in your DNS to check it. See DKIM records, explained.
DMARC	Domain-based Message Authentication, Reporting & Conformance. A DNS policy that tells email servers what to do with messages that fail SPF or DKIM checks. See DMARC records, explained.
DNS	Domain Name System. The internet's address book: translates human-readable domain names into IP addresses. See What is DNS?.
DNS propagation	The time it takes for a DNS change to reach DNS servers around the world. How long depends on the record's TTL; for a nameserver change registrars commonly tell you to allow 24 to 48 hours. See DNS propagation.
DNS record	An instruction in your domain's DNS settings. Different record types control different things (where the site points, where email goes, etc.).
DNS zone	The collection of all DNS records for a domain. Managed in your DNS provider's dashboard.
Domain	The human-readable address for your website, e.g. yourcompany.com. See What is a domain name?.
Domain extension	The suffix at the end of a domain: .com, .org, .net, .io. Also called a TLD (Top-Level Domain). Some countries add a level below their own, so a UK business address often ends .co.uk: there the top-level domain is still .uk, with .co a level below it.
Domain locking	A security feature that prevents unauthorized transfers. Most domains should be locked except when actively transferring.
Domain privacy	A service that keeps your personal contact details out of the public registration record. Also called WHOIS privacy or privacy protection. See Domain privacy protection explained.
Domain registrar	The company where you registered your domain: GoDaddy, Namecheap, Cloudflare, Squarespace, and many others. Google Domains no longer exists: Squarespace took over all of its registrations in September 2023.
Domain transfer	Moving a domain from one registrar to another. Requires the auth code and unlocking the domain.
Expired domain	A domain whose registration has lapsed. It may go into a grace period, then become available for others to buy.
Forwarding	Redirecting a domain or URL to another address. www.yoursite.com forwarding to yoursite.com is a common example.
Glue record	A special DNS record needed when your nameservers are within the same domain (e.g. ns1.yoursite.com). Prevents a chicken-and-egg lookup problem.
Grace period	Properly the "auto-renew grace period": an optional window right after your domain expires in which your registrar still lets you renew, sometimes for a post-expiry fee. Each registrar sets its own length, so plan on about 30 days and never count on more. If the registrar then deletes the domain, a separate 30-day Redemption Grace Period follows in which only you can restore it, usually for a higher restore fee. See What happens when a domain expires.

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H to N

Term	Plain-English definition
ICANN	Internet Corporation for Assigned Names and Numbers. The non-profit that coordinates the internet's naming systems, including registration policy for generic extensions like .com and the root DNS zone.
IP address	A unique numerical address for a server. DNS translates your domain name into this address so browsers know where to go.
MX record	Mail Exchange record. Tells email servers where to deliver email for your domain: points to your email provider.
Nameserver	A server that holds the DNS records for a domain. When you "point your domain" to a host, you usually update the nameservers.
Nameserver delegation	Handing control of your domain's DNS to a specific nameserver: usually your hosting provider's or Cloudflare's.
NS record	The DNS record type that lists your domain's nameservers.

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P to R

Term	Plain-English definition
Parked domain	A registered domain that doesn't point to an active website yet. Often shows a placeholder page.
Pointing	Changing DNS records so your domain directs visitors to a new server or service.
Propagation	See DNS propagation above. The delay while changes spread worldwide.
Redirect	Automatically sending visitors from one URL to another. A 301 redirect is permanent; a 302 is temporary.
Registrant	The person or company legally registered as the domain owner.
Registrar	See Domain registrar. The company that manages your domain registration.
Registry	The organization that manages a top-level domain (TLD) like .com, .org, or .uk. Registrars sell to customers on the registry's behalf.
Renewal	Paying to extend your domain registration for another year (or more).
Root domain	The core domain without any subdomain prefix: yourcompany.com rather than www.yourcompany.com.

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S to Z

Term	Plain-English definition
SOA record	Start of Authority. Technical record that defines the primary nameserver and administrative details for a DNS zone. You rarely need to touch this.
SPF record	Sender Policy Framework. A DNS TXT record that lists which servers are allowed to send email on behalf of your domain. See SPF records, explained.
SSL/TLS	The encryption that makes HTTPS work. "SSL" is the everyday name; today's connections actually use its successor, TLS. Your hosting provider usually sets this up.
Subdomain	A prefix added before your main domain: blog.yoursite.com, shop.yoursite.com. See Subdomains explained.
TLD	Top-Level Domain. The last part of a domain name: .com, .org, .net, .io, .shop, .uk. In an address like example.co.uk the TLD is .uk; .co is one level below it, not part of the TLD.
TTL	Time To Live. How long (in seconds) DNS servers around the world cache a DNS record before re-checking it. Lower = faster updates; higher = less load.
TXT record	A flexible DNS record that can hold any text value. Used for domain verification, SPF, DKIM, and more.
Transfer	See Domain transfer. Moving a domain between registrars.
WHOIS	The original public directory of domain registration details: the registrar, the expiry date, the nameservers. ICANN says that since 28 January 2025, RDAP (the Registration Data Access Protocol) is the definitive source for generic extensions such as .com, in place of sunsetted WHOIS services, and much registrant contact data is no longer published at all. Most registrars still call the setting "WHOIS privacy." See Domain privacy protection explained.
www	A subdomain prefix (www.yoursite.com). Short for World Wide Web. Most modern sites work with or without it. See www vs non-www.
Zone file	The text file containing all DNS records for a domain. You interact with these records through your registrar or DNS provider's dashboard.

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Common questions

Do I need to understand DNS to manage my website?

What's the difference between a registrar and a DNS provider?

Why do DNS changes take time?

Related guides

• Domains & DNS, explained simplyEverything you need to know about domain names and DNS, from the basics to email records, transfers, and troubleshooting.
• Domains & DNS, explained simplyWhat is DNS?A plain-English explanation of the Domain Name System: how it works, why it matters, and what it has to do with your website and email.
• Domains & DNS, explained simplyDNS records explained (A, CNAME, MX, TXT)A plain-English guide to the four DNS record types you'll encounter most often (A, CNAME, MX, and TXT) and what each one does.
• Domains & DNS, explained simplyEmail DNS records (MX, SPF, DKIM, DMARC)An overview of the four DNS record types that make your business email work correctly and land in inboxes rather than spam.
• Domains & DNS, explained simplyDomain & DNS terms, explained simplyA plain-English A to Z glossary of every domain name and DNS term you're likely to encounter, from A record to WHOIS.
• The plain-English web glossaryWeb basics: terms A to ZThe core vocabulary everyone building or managing a website needs to know, explained in plain English.