Hi I want to get a subdomain setup for one of my domains. I've logged into my account on domainmonster.com and gone to Manage DNS. I noticed that there seem to be 2 places to configure a subdomain (as an A record or as a CNAME).

How do I know which one to use? Are there benefits of one over the other?

Thanks in advance.

Static, an A record is a DNS record that maps a hostname (or subdomain) to an IP address, whereas a CNAME maps a hostname to another hostname.

For example, the www hostname for yourdomain.com could be set with an A record to IP address 192.100.0.1; or a CNAME for www hostname could be set to sub.yourdomain.com or google.com.

There is a slight performance difference - a client machine will want to get to an IP address in order to make a connection, so using CNAMES mean that the client will need to carry out another DNS lookup for each CNAME it encounters (until it gets an IP address).

Using the above example:

Using A records
-> www.yourdomain.com gives A record (192.100.0.1).
-> Done.

Using CNAME records
-> www.yourdomain.com gives CNAME record (google.com)
-> google.com gives A record (64.223.183.147)
-> Done.

So as you can see, each CNAME record causes an extra lookup step in the DNS resolution.

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Domainmonster.com Customer Support Team.
Domain Name Registration Information & Resources.