First of all let's make it clearer, what is meant by "domain name resolution"?
"Domain name resolution" is the process of translating your web address into its corresponding IP address. e.g. translating (www.brainly.com to 104.16.32.180)
Computers cannot understand the human language they only can understand numbers that's why we need this process.
So, the process (in a very simple way) is divided into four steps:
1) Lookup "root nameservers"
2) Lookup "Top Level Domain TDL nameservers"
3) Lookup "domain nameservers"
4) Lookup "subdomain nameservers" [if exist]
If you still confused please check out this video https://www.youtube.com/watch?v=BCjUbpIzRs8&index=10&list=PL4bq-KmCeyBmMvBB3-RT6ikdp8ljV9GeT