What DNS does
DNS translates domain names into technical destinations used by browsers, mail servers and connected services.
A guide toread a DNS zone
| Record | What it does | Key caution |
|---|---|---|
| A / AAAA | What it doesMap a name to an IPv4 or IPv6 address | Key cautionUpdate them when the server changes |
| CNAME | What it doesAliases a name to another hostname | Key cautionIt is not an HTTP redirect |
| MX | What it doesRoutes incoming email | Key cautionRespect priority and keep the active service |
| TXT | What it doesPublishes verification and policies | Key cautionConsolidate SPF into one record |
| CAA | What it doesLimits which CAs may issue TLS | Key cautionAllow your issuer before renewal |
| NS + TTL | What it doesDelegate the zone and control caching | Key cautionPlan changes; propagation is not a fixed timer |
Essential records
A and AAAA point to IP addresses, CNAME creates aliases, MX routes mail, TXT publishes verification policies and CAA limits certificate issuers.
Change DNS safely
Back up the zone, change one target at a time, account for TTL caching and validate results with an external DNS tool.
Verified sources
Go deeper
These two resources expand on the key points with criteria, data and guidance from the organizations responsible for them.
RFC 1034 on DNS concepts
It describes the hierarchical namespace, servers, zones and resolution process that connect a domain to technical resources.
RFC 1035 on DNS implementation
It specifies the message and resource-record formats servers and resolvers use to query and return DNS information.
