There’s absolutely no limit. Some hosting providers add arbitrary limits but even the entire Bitcoin header tree in DNS records running in BIND is like 1G of memory…

https://bitcoinheaders.net/ 

 Any tutorials for beginners? 

 For what? Running bind? 

 Yep. 

 Don’t have a specific one to recommend, but googling “bind authorative server” should turn things up. 

 Thank you. 🙏🏿