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A DNS lookup returns records that tell systems how to find a name and what services handle it. A and AAAA records provide IPv4 and IPv6 addresses, MX routes incoming email, TXT stores service-specific text, NS identifies authoritative nameservers, and CNAME makes one name an alias for another. The correct values for a live domain come from its hosting, email, and DNS providers—not from a generic example.
What each DNS record does
| Record | What it tells DNS | Common use | Important constraint |
|---|---|---|---|
| A | An IPv4 address for a name | Pointing a hostname to an IPv4-capable service | Use the address supplied by the service hosting the site or application. |
| AAAA | An IPv6 address for a name | Making a hostname resolvable over IPv6 | Publish only an IPv6 value valid for the intended service. |
| MX | Mail exchanger hostnames and preference values for a domain | Routing incoming email to a mail provider | Lower numeric preference values are preferred. The target must not be a CNAME alias. |
| TXT | Text associated with a DNS name | Domain ownership checks and email authentication, including SPF, DKIM, and DMARC | The required text and name or host field depend on the service being configured. |
| NS | Nameservers authoritative for a zone or delegated subdomain | Changing authoritative DNS or delegating a subdomain | Delegation is different from adding an ordinary host record; follow the instructions for the intended zone. |
| CNAME | A canonical target name for an alias | Pointing a name such as www to a provider hostname |
Under ordinary DNS rules, a name with a CNAME cannot also carry other record data. |
How A and AAAA records differ
Both record types associate a hostname with an IP address, but A is for IPv4 and AAAA is for IPv6. A hostname can be configured for either protocol or both, provided the addresses are valid for the service. RFC 1035 describes an A record’s address in the familiar form of four decimal numbers separated by dots.
For example, a documentation-only hostname such as www.example.test could have an A record with an illustrative IPv4 address and an AAAA record with an illustrative IPv6 address. Those examples would not tell you what to enter for your own domain; obtain the values from the service that hosts it.
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How MX records route incoming email
An MX record tells sending mail systems which mail exchanger handles email for a domain. It includes a preference value that orders the exchangers: lower numeric values are preferred. Your email provider supplies the hostnames and preference values to enter.
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An MX target must be a hostname with its own address records, not a CNAME alias. Using the provider’s specified hostname avoids an invalid target configuration.
What TXT records are for
TXT records associate text with a DNS name. Services use them for domain ownership checks and email-authentication data such as SPF, DKIM, and DMARC. The content is not interchangeable: use the exact string and DNS name or host field supplied by the service you are configuring. TXT is a record type, not a guarantee that arbitrary text will be meaningful to a receiving service.
What NS records mean for DNS authority
NS records identify the nameservers authoritative for a DNS zone or delegated subdomain. Changing nameserver delegation is not the same as adding an A, MX, or TXT record within a zone. When moving DNS hosting or delegating a subdomain, follow the registrar and DNS host’s instructions for the zone involved.
Cloudflare’s educational guidance notes that multiple nameservers are commonly used and says delegation changes can take several hours to appear throughout DNS. That is practical guidance from one provider, not a guaranteed global timer.
How CNAME aliases work—and their limits
A CNAME makes one DNS name an alias for another name. For example, a service may ask you to point www at a hostname it operates. A CNAME is DNS name resolution; it does not redirect a browser to a different URL. A web redirect is a separate HTTP behavior.
Under ordinary DNS rules, a name carrying a CNAME cannot also carry unrelated record data such as A, MX, TXT, or NS records. RFC 2181 also clarifies that MX and NS targets must not be aliases. Some DNS providers offer features such as CNAME flattening at a zone apex; these are provider-specific behaviors, not a change to the ordinary rule.
A CNAME target may itself resolve through another CNAME in some cases, but chains add lookup steps. When the provider supports it, a direct target is preferable. Follow the DNS provider’s documentation for any provider-specific alias or flattening feature.
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Why a DNS change may not appear immediately
TTL means time to live. It sets how long a resolver may cache a DNS response before checking again. After a change, some users may still receive a previous cached answer while that answer remains valid. TTL does not promise an instant update worldwide, and DNS providers differ in their default values and controls. There is no universal propagation duration to assume.
Where to get the right values for your domain
- For A and AAAA records, use the address values supplied by the service hosting the website or application.
- For MX and related TXT records, use the exact hostnames, priorities, and authentication strings supplied by your email provider.
- For NS changes or subdomain delegation, follow the instructions from both the registrar and the DNS host for the zone you intend to change.
- For a CNAME or provider-specific flattening feature, use the target and configuration instructions from the service receiving the alias.
Cloudflare’s documentation explains record types and its own dashboard features, including proxy status and CNAME flattening; those behaviors apply to Cloudflare’s implementation rather than every DNS provider. Cloudflare DNS record types.
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