Reference article: http://blog.xieyc.com/differences-between-a-record-and-cname-record/
A (Address) record is used to specify the IP address record corresponding to the host name (or domain name). Users can point the website server under the domain name to their own web server. At the same time, you can also set the second-level domain name of your domain name.
CNAME: Alias record. This type of record allows you to map multiple names to another domain name. Usually used for computers that provide both WWW and MAIL services. For example, there is a computer named "host.mydomain.com" (A record). It provides both WWW and MAIL services, in order to facilitate users to access services.
Which one is better for domain name resolution CNAME record A record? When it comes to the impact on the website, it doesn't make much difference. But: one advantage of CNAME is stability, just like the difference between an IP and a domain name. From the perspective of convenient maintenance, service providers generally recommend that users use CNAME records to bind domain names. If the host uses a two-line IP, it is obviously more convenient to use a CNAME.
A record also has some advantages, for example, you can visit the website without entering WWW. when entering the domain name! From the point of view of SEO optimization, some search engines such as alex or some search query tool websites automatically remove WWW. Such trouble, the prefix is removed from the default website and cannot be accessed.
Some people think that when SEO optimizes the website, because the search engine cannot find the domain name without WWW., it will also have some influence on the website weight. Because some netizen customers do not like to write three more W to visit the website, and the website cannot be accessed, a small number of netizen customers will give up and continue to try to add WWW. to visit the domain name, so the number of website visits will also decrease.