Differences Among A, CNAME, ALIAS, and URL records
URL records are all possible solutions to point a host name (“name”) to your site. However, they have small differences that affect how the client reaches your site.
CNAME records are standard DNS records.
URL records are custom DNS records provided by DNSimple’s DNS hosting. Both of them are translated internally into
A records to ensure compatibility with the DNS protocol.
Understanding the differences
These are the main differences:
Arecord maps a name to one or more IP addresses when the IP are known and stable.
CNAMErecord maps a name to another name. It should only be used when there are no other records on that name.
ALIASrecord maps a name to another name, but can coexist with other records on that name.
URLrecord redirects the name to the target name using the HTTP 301 status code.
ALIASrecords cause a name to resolve to an IP. Conversely, the
URLrecord redirects the name to a destination. The
URLrecord is a simple and effective way to apply a redirect for one name to another name, for example redirecting
Aname must resolve to an IP. The
ALIASrecords must point to a name.
Which one to use
Understanding the difference between
A name and
CNAME records will help you decide.
- Use an
Arecord if you manage which IP addresses are assigned to a particular machine, or if the IP are fixed (this is the most common case).
- Use a
CNAMErecord if you want to alias one name to another name, and you don’t need other records (such as
MXrecords for emails) for the same name.
- Use an
ALIASrecord if you’re trying to alias the root domain (apex zone), or if you need other records for the same name.
- Use the
URLrecord if you want the name to redirect (change address) instead of resolving to a destination.
You should never use a CNAME record for your root domain name (e.g. example.com).