assume a website is aliased. for instance www.sunnyweather.com is the alias and CNAME is xyzverycomplex.sunnyweather.com. After you query and get the CNAME you then need to query the A Type for the xyzverycomplex.sunnyweather.com . the question is: why do I should care about the CNAME? why I can't get directly the IP address of the alias from the name server?
You can do both.
If you use A records for all your ip addresses you must change each and every record affected every time you need to change the ip address, e.g., when you change the ip address of a server.
Using CNAME records enable you to group the ip addresses in a logical way so you often only need to change a few entries, e.g., an A record to change all the references to a server.