Homebrew DNS Question

[q] I have an older 3DS that still has the 9.5 and below requirements for the QR code PkHex. Right now I've been using OpenDNS in order to block the 3ds from updating.

On the Homebrew website it says that their DNS blocks not only the update but from being able to use the EShop.

My question is if I change the DNS to the one from Homebrew would it stop my 3DS from updating to where I won't have to use the OpenDNS? Is the DNS for Homebrew enough or do I have to have Homebrew set up on my SD card for the DNS to work? Would be required to have the Youtube app?