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