Questions regarding block user agents in apache,nginx,varnish

Hello, i am using Centos-Webpanel and i am really lovin it.
I am using Varnish as frontend then nginx and at end Apache.
I am facing a problem that my website is getting HTTP flood i have a question if i ban a user agent in apache config does varnish will also dont allow that user agent from accessing my website ? or if i ban user agent in nginx conf does user will be able to access website because i am using varnish on port 80

http://omninoggin.com/web-development/block-unwanted-spam-bots-using-varnish-vcl/

https://www.section.io/2015/09/24/using-varnish-to-tweak-your-http-responses.html