22 terms · in English & Greek

Glossary
DNS, Email & Domain

Clear, concise explanations of terms you encounter in our tools — from SPF and DKIM to DNSSEC and HSTS.

DNS & Records

10 terms

How the Domain Name System works and what the main record types are.

DNS — Domain Name System
The "phone book" of the Internet: translates domain names into IP addresses.
A Record
DNS record that maps a hostname to an IPv4 address.
CNAME — Canonical Name
DNS record that acts as an alias: points one hostname to another.
MX Record
DNS record that specifies which mail servers receive email for the domain.
TXT Record
Free-text DNS record — used for SPF, DKIM, DMARC and domain verification tokens.
NS Record — Nameserver
DNS record that specifies the authoritative nameservers for a domain.
TTL — Time To Live
How long (in seconds) a DNS record can be cached by a resolver.
DNSSEC — DNS Security Extensions
Cryptographic signing of DNS responses to prevent tampering and cache poisoning.
CAA Record
Specifies which Certificate Authorities are allowed to issue SSL certificates for your domain.
PTR Record — Reverse DNS
Reverse lookup: returns the hostname associated with an IP address.

Email Authentication

6 terms

SPF, DKIM, DMARC and the modern standards for secure email delivery.

SPF — Sender Policy Framework
Standard that declares which mail servers are permitted to send email on behalf of your domain.
DKIM — DomainKeys Identified Mail
Cryptographic signature on emails verifying they were genuinely sent from the domain.
DMARC — Domain-based Message Authentication
Policy that tells receivers what to do with emails that fail SPF/DKIM checks.
MTA-STS — SMTP Strict Transport Security
Enforces encrypted TLS delivery for incoming emails to the domain.
TLS-RPT — SMTP TLS Reporting
Reporting mechanism for TLS failures during email delivery.
BIMI — Brand Indicators for Message Identification
Displays your logo next to emails in Gmail/Yahoo, provided you have a valid DMARC policy.

Security & TLS

3 terms

SSL/TLS, HTTP security headers and web protection standards.

SSL / TLS
Encryption protocol securing the connection between browser and server. SSL is obsolete; TLS is its successor.
HSTS — HTTP Strict Transport Security
HTTP header that forces browsers to always connect via HTTPS.
CSP — Content Security Policy
HTTP header that restricts which sources a page can load — protection against XSS attacks.

Domain Industry

3 terms

WHOIS, registrars, registries and the ecosystem around domain names.

WHOIS
Protocol and database that shows domain details: registrar, dates, nameservers and status.
Registrar — Καταχωρητής
The company from which you buy/renew domains. Different from the registry.
TLD — Top-Level Domain
The suffix of a domain (.gr, .com, .org). Managed by a registry.