GLOSSARY
What Is an A Record
Learn what an A record is, how it points a domain to an IPv4 address, when to change it, and how to check A records safely.
Glossary Guides
Simple definitions for DNS, email, SSL, website health and hosting terms.
Topics covered:
DNS recordsEmail authSSL/TLSWHOIS
27 articles
All Glossary guides
27 guides covering glossary topics.
GLOSSARY
What Is an AAAA Record
Learn what an AAAA record is, how it maps hostnames to IPv6 addresses, and when AAAA records matter for websites and DNS.
GLOSSARY
What Is a CNAME Record
Learn what a CNAME record is, how DNS aliases work, common uses for www and CDN hostnames, and CNAME restrictions.
GLOSSARY
What Is an MX Record
Learn what an MX record is, how incoming email routing works, MX priority, and how MX differs from website DNS records.
GLOSSARY
What Is an NS Record
Learn what NS records are, how nameservers work, authoritative DNS, and why nameserver changes affect your entire zone.
GLOSSARY
What Is a TXT Record
Learn what TXT records are, how they are used for SPF, DKIM, DMARC, domain verification, and common TXT record mistakes.
GLOSSARY
What Is an SOA Record
Learn what an SOA record is, what Start of Authority means, zone serial numbers, refresh timers and SOA best practices.
GLOSSARY
What Is a CAA Record
Learn what CAA records are, how they control SSL certificate issuance, issue vs issuewild, and common CAA mistakes.
GLOSSARY
What Is a PTR Record
Learn what a PTR record is, how reverse DNS works, mail server identity, and why PTR is set by your IP provider.
GLOSSARY
What Is a Subdomain
Learn what subdomains are, common examples like www and mail, DNS records per subdomain, and SSL considerations.
GLOSSARY
What Is TTL
Learn what DNS TTL means, how caching works, migration planning, and common TTL mistakes.
GLOSSARY
What Is DNS Propagation
Learn what DNS propagation means, resolver cache, TTL, authoritative DNS, and how to tell propagation from misconfiguration.
GLOSSARY
What Is SPF
Learn what SPF is, how it authorizes email senders, SPF pass/fail, the 10 lookup limit, and how SPF relates to DMARC.
GLOSSARY
What Is DKIM
Learn what DKIM is, how email signing works, selectors, public keys in DNS, and how DKIM supports DMARC alignment.
GLOSSARY
What Is DMARC
Learn what DMARC is, how policies work, alignment with SPF and DKIM, reporting, and safe enforcement progression.
GLOSSARY
What Is MX Priority
Learn what MX priority means, how lower numbers indicate higher priority, backup MX, and common priority mistakes.
GLOSSARY
What Is a DKIM Selector
Learn what a DKIM selector is, how to find it in headers, selector._domainkey DNS records, and key rotation.
GLOSSARY
What Is BIMI
Learn what BIMI is, brand logo display in email, DMARC requirements, SVG logos, and VMC considerations.
GLOSSARY
What Is Reverse DNS
Learn what reverse DNS is, how PTR records work, mail server identity, and forward-confirmed rDNS.
GLOSSARY
What Is SSL/TLS
Learn what SSL/TLS and HTTPS are, how certificates work, expiry, chains, hostname validation, and common TLS mistakes.
GLOSSARY
What Is HSTS
Learn what HSTS is, Strict-Transport-Security headers, max-age, includeSubDomains, preload, and safe rollout.
GLOSSARY
What Is DNSSEC
Learn what DNSSEC is, how DNS signing works, DS records, validation failures, and what DNSSEC does not protect.
GLOSSARY
What Is WHOIS
Learn what WHOIS and RDAP are, what registration data they show, domain status codes, and how WHOIS differs from DNS.
GLOSSARY
What Is a Registrar
Learn what a domain registrar is, how registration differs from hosting and DNS, renewals, transfers, and locks.
GLOSSARY
What Is a DNSBL
Learn what a DNSBL is, how email blacklists work, IP and domain listings, delisting, and reputation impact.
GLOSSARY
What Is a CDN
Learn what a CDN is, edge caching, performance benefits, DNS integration, SSL at the edge, and cache pitfalls.
GLOSSARY
What Is a Domain Health Check
Learn what a domain health check covers, including DNS, email auth, SSL, MX, blacklist signals, and expiry checks.
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