CNames versus A Records versus ALIASES

All three (CNames, A Records and Aliases) map names to IP Addresses. The difference between these is:

  • The A record maps a name to one or more IP addresses, when the IP are known and stable.
  • The CNAME record maps a name to another name. It should only be used when there are no other records on that name.
  • The ALIAS record maps a name to another name, but in turns it can coexist with other records on that name.

 

The general rule is:

  • use an A record if you manage what IP addresses are assigned to a particular machine or if the IP are fixed (this is the most common case)
  • use a CNAME record if you want to alias a name to another name, and you don’t need other records (such as MX records for emails) for the same name
  • use an ALIAS record if you are trying to alias the root domain (apex zone) or if you need other records for the same name
  • use the URL record if you want the name to redirect (change address) instead of resolving to a destination.

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