Glossary
The domain name glossary
Twenty words that turn up in every site handover, every migration, and every client asking why their email lands in spam. Each one defined in a sentence you can paste straight into an email, with the example that goes with it and the mistake people make most often.
The domain name
Who sells the name, who holds it, who can move it. This is the layer where site handovers and the end of a client relationship play out.
Registrar
The company you buy a domain name from, and renew it with.
Registry
The organization that runs an extension and keeps the authoritative list of its names.
WHOIS
The legacy service that shows who registered a domain, and for how long.
RDAP
The replacement for WHOIS: the same data, in JSON and over HTTPS.
Transfer lock
The status that makes a domain refuse to move to another registrar.
DNS
The machinery that turns a name into an address. It is what you edit for a migration, and what keeps you waiting when you go about it the wrong way.
Name server
The machine that answers authoritatively for a domain.
DNS zone
All of a domain's records, held by one and the same manager.
A record
The line that ties a name to an IPv4 address — the domain to the actual machine.
CNAME record
An alias: this name is really that other name.
TXT record
Free text attached to a domain — this is where
SPF,DKIMandDMARClive.TTL (time to live)
How many seconds a DNS answer may be kept in cache.
DNS propagation
The everyday word for the wait after a change — although nothing propagates.
The records that decide where a domain's mail arrives, and who is allowed to send in its name.
Security and reputation
What proves a domain is the one it claims to be, and what happens when somebody doubts it.
DNSSEC
Signatures proving a DNS answer was not tampered with in transit.
TLS certificate
The signed file that ties a domain name to a key, and makes HTTPS work.
Certificate authority
The body that checks a name is yours, then signs the certificate.
Blacklist
A directory of flagged addresses or domains, checked before mail is accepted.
Every definition is checked against the standard that defines it or the body that runs it, and each page names its source. Where two sources tell different stories, the entry says so rather than picking one for you.