DNS Record Types Explained
A practical explanation of common DNS record types and what each one does.
DNS records are instructions stored in authoritative nameservers that tell the internet how to handle requests for a domain. Different record types serve different purposes -- from mapping domain names to IP addresses to configuring email delivery and verifying domain ownership.
A Record
An A record maps a hostname to an IPv4 address. This is the most fundamental DNS record type and is what allows a browser to find the server hosting a website. A domain can have multiple A records to enable load balancing or failover. Example: example.com A 93.184.216.34
AAAA Record
An AAAA record is the IPv6 equivalent of an A record. It maps a hostname to a 128-bit IPv6 address. As IPv6 adoption grows, AAAA records are increasingly important for ensuring connectivity. Example: example.com AAAA 2606:2800:220:1:248:1893:25c8:1946
MX Record
MX (Mail Exchange) records specify which servers handle email delivery for a domain. Each MX record includes a priority value -- lower numbers indicate higher priority. This allows domains to define primary and backup mail servers.
TXT Record
TXT records store arbitrary text data in DNS. They are widely used for domain verification (proving ownership to services like Google or Microsoft), SPF email authentication policies, DMARC policies, DKIM key references, and other service-specific configurations.
NS Record
NS (Name Server) records identify the authoritative DNS servers for a domain. These records are critical for delegation -- they tell the DNS hierarchy which servers can provide definitive answers about a domain's records.
CNAME Record
A CNAME (Canonical Name) record creates an alias from one hostname to another. When a resolver encounters a CNAME, it follows the chain to the target hostname and resolves that instead. CNAMEs cannot be placed at the zone apex (the bare domain) alongside other record types.
SOA Record
The SOA (Start of Authority) record contains metadata about the DNS zone, including the primary nameserver, the zone administrator's email address, the zone serial number, and timing values for refresh, retry, expire, and negative caching TTL.
CAA Record
CAA (Certificate Authority Authorization) records specify which certificate authorities are permitted to issue SSL/TLS certificates for a domain. This helps prevent certificate mis-issuance by unauthorized CAs.
SRV Record
SRV (Service) records advertise the hostname and port number for specific services, such as SIP, XMPP, or LDAP. They include priority and weight values to support load balancing and failover for service discovery.