Record Types
What is a DNS A record?
An A (Address) record maps a hostname to an IPv4 address (e.g. 93.184.216.34). It is the most fundamental DNS record type — it tells browsers and other clients which server to connect to when a domain name is requested.
What is a DNS AAAA record?
A AAAA record maps a hostname to an IPv6 address (e.g. 2606:2800:220:1:248:1893:25c8:1946). It is the IPv6 equivalent of the A record. Domains increasingly publish both A and AAAA records to support dual-stack (IPv4 + IPv6) connectivity.
What is a DNS MX record?
An MX (Mail Exchange) record specifies the mail server responsible for accepting email for a domain. Each MX record includes a priority value — the lower the number, the higher the priority. Multiple MX records can be configured for redundancy and failover.
What is a DNS TXT record?
A TXT (Text) record stores arbitrary text data for a domain. TXT records are the backbone of email security: SPF records authorize which servers may send email on behalf of a domain, DKIM records publish cryptographic keys for signature verification, and DMARC records define policies for handling unauthenticated email.
What is a DNS NS record?
An NS (Name Server) record lists the authoritative nameservers for a domain — the servers that hold the official DNS zone data. When you register a domain, NS records are configured to point to your registrar's or hosting provider's nameservers.
What is a CNAME record?
A CNAME (Canonical Name) record creates an alias from one domain to another. For example, www.example.com may CNAME to example.com. CNAME records cannot be used at a domain's apex (the bare root domain) and cannot coexist with other record types at the same hostname.
What is a DNS SOA record?
An SOA (Start of Authority) record contains administrative metadata for a DNS zone: the primary nameserver address, the zone administrator's email, a serial number used to detect changes, and timing parameters for zone refresh, retry, expiry, and minimum TTL.
What is a PTR record?
A PTR (Pointer) record maps an IP address back to a hostname — the reverse of an A or AAAA lookup. PTR records live in the .in-addr.arpa (IPv4) or .ip6.arpa (IPv6) namespace. Mail servers use them to verify sender identity; network teams use them for diagnostics and abuse investigation.
What is a DNS SRV record?
An SRV (Service) record specifies the hostname and port for a specific network service such as SIP, XMPP, or Microsoft Teams. It includes priority, weight, port, and target fields, enabling clients to discover service endpoints without hard-coded configuration.
What is a CAA record?
A CAA (Certification Authority Authorization) record declares which certificate authorities (CAs) are permitted to issue SSL/TLS certificates for a domain. Any CA not listed must refuse issuance, reducing the risk of fraudulent certificate creation.
DNS Concepts
What is DNS propagation?
DNS propagation is the time it takes for a DNS record change to spread across all resolvers worldwide. Because DNS responses are cached according to their
TTL, changes can take anywhere from minutes to 48 hours to be universally visible. During propagation, different users may see different values depending on which resolver they use. →
Full propagation guide
What is TTL in DNS?
TTL (Time To Live) is a value in seconds that tells DNS resolvers how long to cache a record before requesting a fresh copy from the authoritative nameserver. A low TTL (e.g. 300 s) speeds up propagation of changes but generates more queries. A high TTL (e.g. 86400 s = 24 hours) reduces query load but slows propagation.
What is a CNAME chain?
A CNAME chain occurs when one CNAME points to another CNAME, which in turn points to yet another name, before finally resolving to an A or AAAA record. Chains are common in CDN and load-balancer setups. Each hop adds a resolution step — keep chains to three hops or fewer for best performance.
What is an authoritative nameserver?
An authoritative nameserver is the DNS server that holds the original, definitive records for a domain zone. Unlike recursive resolvers (e.g. Google 8.8.8.8 or Cloudflare 1.1.1.1), which cache and relay answers, an authoritative nameserver always returns the current record values with no caching layer in between.
What is a reverse DNS lookup?
A reverse DNS lookup queries a PTR record to find the hostname associated with a given IP address. For example, a reverse lookup for 8.8.8.8 returns dns.google. It is used by mail servers to verify sender identity, and by network administrators for diagnostics and abuse investigation.
Resolvers
What is the difference between Google DNS (8.8.8.8) and Cloudflare DNS (1.1.1.1)?
Both are free public recursive DNS resolvers. Cloudflare DNS (1.1.1.1) generally offers lower latency and a strong privacy policy (query logs deleted within 24 hours). Google Public DNS (8.8.8.8) has extensive global infrastructure and a long reliability track record. Querying the same domain through both resolvers is a practical way to check whether a DNS change has propagated.
When should I use the authoritative nameserver option?
Use the authoritative nameserver option when you want to see the live, uncached value of a DNS record — for example, immediately after making a change at your registrar or hosting provider. If the authoritative nameserver and a public resolver return different results, the change is still propagating through the caching infrastructure.