What is CNAME? · Ultra Transcenders glossary

Alias record in DNS that points one name at another, for example www at <app>.azurewebsites.net; it can't be placed at the apex of a zone.

Also called canonical name record.

In the Ultra Transcenders books

Each book explains CNAME in context, with comparison tables and the common traps.

Alias record
In Azure DNS, a record set that targets an Azure resource itself (say, a CDN endpoint or public IP) rather than a fixed address, so it stays correct whenever that resource gets a new IP. Bare apex domains can use one to reach such a resource.
DNS
The system that turns names into addresses. In Azure, private endpoints depend on private DNS zones, which are queried through 168.63.129.16.
App protection policy
A set of Intune rules on managed apps that safeguards organisational data, for example by demanding a PIN or preventing copy-paste and save-as into personal apps. It works whether or not the device is enrolled.

afdverify
Verification CNAME in Front Door (classic), mapping afdverify.<host> to afdverify.<name>.azurefd.net, which proves ownership of a custom domain while live traffic stays where it is.
Apex domain
The bare domain without any subdomain (example.com), also known as the zone apex or root domain. Since a CNAME is not allowed there, routing it to a service like Front Door relies on CNAME flattening or Azure DNS alias records.
App Service custom domain
Host name bound to an App Service app once the service has confirmed an asuid TXT record and an A or CNAME record. Serving it over HTTPS also requires binding a TLS certificate.
Custom domain
A DNS name of your own attached to a service. In an Entra tenant it is verified through a TXT or MX record, and every on-premises UPN suffix used to sign in must be one (.local can't be); for App Service it is bound with CNAME or TXT validation.
DNAME
A DNS record that points an entire branch of the namespace at a different domain, whereas a CNAME only gives a single name an alias.
Endpoint (Front Door)
Host name in Front Door Standard/Premium, shaped like <name>-<hash>.z01.azurefd.net, to which routes are attached and custom domains point by CNAME.
privatelink zone
Private DNS zone holding a private endpoint's A record, named after the privatelink CNAME target of the service, for instance privatelink.database.windows.net for Azure SQL Database. Naming it after the public suffix is wrong.