Why too many automatisms in DNS are bad (Pi-hole, FTL (dns.reply.host), mDNS/Avahi, etc.)

A small pre-preface for users who followed the "Ultimate Pi-hole Setup" tutorial from the YouTuber WunderTech If you used the configuration files he provided on his homepage: https://www.wundertech.net/ultimate-pi-hole-setup/ you will experience the exact same problems sooner or later. The reason is that the VIPs from keepalived are not bound on a separate dummy interface and hence the pihole-FTL…