DNS Record Types Explained: A, AAAA, MX, TXT, CNAME, NS, SOA and More

Every domain on the internet is held together by DNS records — small pieces of configuration data that tell the internet what to do with requests for your domain. Change the wrong record and your website goes down. Delete the right record and your email stops working. Add the right TXT record and your email deliverability improves dramatically.

This guide explains every major DNS record type, what it does, and when you'd use it.

A Record — IPv4 Address

The A record is the most fundamental DNS record. It maps a domain name to an IPv4 address — the 32-bit address format like 93.184.216.34. When someone visits example.com, their browser queries DNS for the A record to find where to connect.

Format:

example.com.    300    IN    A    93.184.216.34

Common uses:

• Pointing your root domain (example.com) at your web server's IP address
• Pointing a subdomain (shop.example.com) at a separate server
• Multiple A records for the same domain (load balancing / redundancy)

A domain can have multiple A records — this is used for simple DNS-based load balancing. Each query will return all of them, and the requesting system typically tries them in order or rotates through them.

AAAA Record — IPv6 Address

The AAAA record does the same thing as an A record, but for IPv6 addresses — the 128-bit format that looks like 2606:2800:220:1:248:1893:25c8:1946. IPv6 was developed because the internet was running out of IPv4 addresses.

Format:

example.com.    300    IN    AAAA    2606:2800:220:1:248:1893:25c8:1946

Most modern websites serve both A and AAAA records. When a user with IPv6 connectivity visits your domain, their browser will prefer the AAAA record. IPv6-only users (rare now, but growing) require an AAAA record to reach your site at all.

CNAME Record — Canonical Name

A CNAME record creates an alias from one domain name to another. Instead of pointing to an IP address, it points to another domain name (the "canonical" name) which is then resolved normally.

Format:

www.example.com.    300    IN    CNAME    example.com.
blog.example.com.   300    IN    CNAME    mysite.wordpress.com.

Common uses:

• Making www.example.com an alias for example.com
• Pointing a subdomain at a third-party service (Shopify, HubSpot, etc.)
• Pointing a subdomain at a CDN hostname

Important constraint: A CNAME cannot coexist with other records for the same name. You cannot have a CNAME on example.com itself (the root domain) because the root domain also needs an SOA record, NS records, and possibly MX records. CNAME records are therefore limited to subdomains. Some DNS providers offer "CNAME flattening" or "ALIAS" records to work around this for the root domain.

MX Record — Mail Exchanger

MX records tell the internet which mail servers should receive email sent to your domain. When someone sends an email to user@example.com, the sending mail server queries DNS for the MX records of example.com to find where to deliver it.

Format:

example.com.    3600    IN    MX    10    mail1.example.com.
example.com.    3600    IN    MX    20    mail2.example.com.

The number before the mail server hostname is the priority. Lower numbers have higher priority — mail is first tried at mail1.example.com, and only falls back to mail2.example.com if the first is unavailable. Having multiple MX records with different priorities provides mail redundancy.

Common uses:

• Pointing email to Google Workspace (Gmail for business)
• Pointing email to Microsoft 365
• Pointing email to your own mail server
• Setting up mail redundancy with multiple records at different priorities

TXT Record — Text Data

TXT records store arbitrary text data associated with a domain. Originally intended for human-readable notes, they have become the standard mechanism for domain verification and email authentication.

Format:

example.com.    3600    IN    TXT    "v=spf1 include:_spf.google.com ~all"
example.com.    3600    IN    TXT    "google-site-verification=abc123..."

Common uses:

• SPF (Sender Policy Framework): Specifies which mail servers are authorised to send email from your domain. Helps prevent your domain from being used for spam.
• DKIM (DomainKeys Identified Mail): A public key that receiving mail servers use to verify the cryptographic signature on outgoing emails.
• DMARC: A policy record that tells receiving mail servers what to do with emails that fail SPF or DKIM checks.
• Domain verification: Services like Google, Microsoft, and many SaaS providers ask you to add a TXT record to prove you own the domain.

A domain can have multiple TXT records. Each serves a different purpose and coexists with the others.

NS Record — Nameserver

NS records specify which DNS servers are authoritative for a domain — the servers that hold the actual DNS records and respond to queries about that domain.

Format:

example.com.    86400    IN    NS    ns1.nameserver.com.
example.com.    86400    IN    NS    ns2.nameserver.com.

When you register a domain, the registrar points the domain's NS records at their own nameservers (or lets you specify custom ones). If you migrate to a different DNS provider, you change the NS records at the registrar, and the internet gradually updates which servers it asks about your domain.

NS records have high TTLs (typically 24–48 hours) because changing them is a significant operation — changing nameservers means the entire set of DNS records for your domain is moving.

SOA Record — Start of Authority

The SOA record is a required record that provides administrative information about a DNS zone. It identifies the primary nameserver for the zone, the email address of the zone administrator (with @ replaced by .), and several timing parameters that control how secondary nameservers sync with the primary.

Format:

example.com.    3600    IN    SOA    ns1.nameserver.com. admin.example.com. (
                                        2026041801  ; Serial
                                        7200        ; Refresh
                                        3600        ; Retry
                                        1209600     ; Expire
                                        300 )       ; Minimum TTL (negative caching)

The minimum TTL in the SOA record controls how long resolvers can cache a "no record found" (NXDOMAIN) response. If you're creating new DNS records, a low minimum TTL here helps new records become visible faster.

Most hosted DNS providers manage the SOA record automatically. You rarely need to edit it directly unless you're running your own nameservers.

PTR Record — Reverse DNS

PTR (pointer) records work in reverse: they map an IP address back to a domain name. This is called reverse DNS lookup. They live under the .in-addr.arpa (IPv4) or .ip6.arpa (IPv6) namespace.

Common uses:

• Mail server reputation: Many receiving mail servers check that the sending server's IP has a PTR record matching its hostname. Missing or mismatched PTR records contribute to mail going to spam.
• Network diagnostics: Tools like traceroute and ping resolve IP addresses to hostnames using PTR records, making network paths readable.

PTR records are controlled by whoever owns the IP address block — usually your hosting provider or ISP — not your domain registrar. To set a PTR record, you typically request it through your hosting control panel or by contacting your provider.

SRV Record — Service Locator

SRV records specify the hostname and port for specific services. They're used by protocols that need to discover where a service is running without hardcoding a port.

Format:

_sip._tcp.example.com.    3600    IN    SRV    10 20 5060 sipserver.example.com.

The format is: priority, weight, port, target hostname. Common uses include SIP (VoIP), XMPP (messaging), and Microsoft 365 (Skype for Business, Teams).

CAA Record — Certification Authority Authorization

CAA records specify which certificate authorities (CAs) are permitted to issue SSL/TLS certificates for your domain. A CAA record that allows only Let's Encrypt, for example, prevents any other CA from issuing a fraudulent certificate for your domain.

Format:

example.com.    3600    IN    CAA    0 issue "letsencrypt.org"

How to Check Any DNS Record

Our DNS Checker lets you look up any record type for any domain across four major public resolvers (Google, Cloudflare, Quad9, OpenDNS) simultaneously. It's useful for verifying that a record exists, checking propagation after a change, or debugging email delivery issues by checking MX and TXT records.