Dale, Am 03.04.2018 um 16:17 schrieb Dale Smith:
I'm trying to understand what system is at fault here; the DNS server for not responding with the same case as the query, or HAProxy which should be performing a case insensitive match.
This is left unspecified in the standards, but on the other hand there is this Internet Draft: https://tools.ietf.org/html/draft-vixie-dnsext-dns0x20-00 which wants to mandate case preserval to make DNS spoofing harder by introducing more entropy in the DNS request.
I recommend to fix your internal DNS server, because case preserving behaviour seems to be somewhat expected according to a quick Google search.
Best regards Tim Düsterhus