DNS record types organized by purpose

DNS records are typed data associated with owner names. Grouping record types by job is more useful than memorizing one alphabetical list.

Read the common record shape

A presentation-format record usually has these parts:

owner-name.  TTL  CLASS  TYPE  RDATA

For example:

www.example.com.  300  IN  A  192.0.2.10

• Owner name: where the record exists in the namespace.
• TTL: the maximum cache lifetime supplied with the record.
• Class: normally IN for Internet data.
• Type: the record’s defined structure and meaning.
• RDATA: the type-specific value.

Records with the same owner, class, and type form an RRset. DNS terminology and protocol documents define how records and RRsets behave [3].

Address a host

Type	Purpose	Important limit
A	Associate an owner name with an IPv4 address	Does not contain a URL, port, or protocol
AAAA	Associate an owner name with an IPv6 address	Does not imply the service is reachable over IPv6

An address answer gets a client to an IP layer. TLS, HTTP, SMTP, and other application behavior still need separate verification.

Alias or direct a service

Type	Purpose	Important limit
CNAME	Make one owner name an alias of another canonical name	Has owner-name coexistence restrictions; it is not an HTTP redirect
SRV	Publish a service target and port with priority and weight	Only helps applications defined to use that SRV naming scheme

Some providers offer apex “flattening” or proprietary alias features. Label those as provider behavior; do not call them standard CNAME records at the zone apex.

Define zone authority and delegation

Type	Purpose	Important limit
NS	Identify authoritative nameservers or form delegation data	Parent and child NS data have different authority
SOA	Describe zone authority and operational parameters	The serial is not a universal content version

Glue is address data supplied in a parent referral to make certain nameserver dependencies reachable. It is a role played by A or AAAA records in that delegation context, not a separate RR type.

Direct email and publish mail policy

Type	Purpose	Important limit
MX	Rank mail exchangers for a domain	Does not prove that SMTP delivery or a mailbox works
TXT	Carry text used by protocols and verification systems	The type itself gives the text no universal meaning

SPF is published in TXT records. DKIM selectors and DMARC policy also use TXT at specific owner names. Each protocol defines its own syntax; a syntactically valid TXT record is not automatically a valid mail policy.

Express certificate or ownership policy

Type	Purpose	Important limit
CAA	Constrain which certificate authorities may issue for a name	Does not issue, renew, or validate a certificate
TXT	Carry provider verification tokens or protocol policy	Old tokens can outlive the service that requested them

Verification records should have an owner, purpose, and removal review. Avoid accumulating unexplained TXT records.

Reverse-map an address

PTR associates a name in the reverse DNS tree with another domain name. Control usually belongs to the IP address provider, not the forward DNS host.

Forward A or AAAA and reverse PTR records are independent. Matching them can support operational policy, but one does not automatically create the other.

Authenticate DNS data

Type	Purpose
DNSKEY	Publish keys for a signed zone
DS	Connect a parent zone to selected child DNSKEY material
RRSIG	Carry signatures over RRsets
NSEC / NSEC3	Authenticated denial of existence

DNSSEC authenticates DNS data and denial responses. It does not encrypt an ordinary DNS query and does not make application content trustworthy.

The registry is larger than this map

IANA maintains the authoritative DNS Parameters registry, including resource record type codes and status [1]. RFC 1035 defines several foundational record formats [2].

Types such as SVCB, HTTPS, TLSA, SSHFP, NAPTR, and others solve specific protocol needs. Add one because a consuming protocol requires it, not because a DNS control panel offers it.

Ask five questions before editing a record

1. What exact owner name will be queried?
2. Which protocol consumes this record type?
3. Who controls the zone that contains the owner?
4. What old RRset and TTL may still be cached?
5. How will the consuming service be verified after DNS answers?

The value shown in a control panel is proposed configuration. An authoritative query proves what the DNS service actually publishes.

Next step

Use the A record reference to begin the record-by-record path, or understand how TTL, positive and negative caches, and resolver refresh timing affect when record changes are observed.