Dig command ussage?

I have use dig command many times to find the subdomain take over vulnerability when i satisfy my results, its good, but i am little bit confused with that format please take a look,

Command:- dig docs.domain.com

docs.domain.com. 10799 IN CNAME domain.github.io.

domain.github.io. 1014 IN CNAME xxx.github.xxx.fastly.net.

xxx.github.xxx.fastly.net. 18 IN A IPaddress

How should i understand the format?

Thank you