* Rich Felker: > This is true for users running local nameservers, which ideally will > eventually be everyone, but at present that's far from the case. > Differences like concurrent attempts from multiple nameservers and/or > lack of TCP fallback on TC are what makes netstat fast on musl vs > repeatedly stalling for multiple seconds at a time on other > implementations. I don't have any data on how often TC happens and if > it's actually a big part of the difference, so this is probably worth > exploring. But I think it's a separate topic from the issue with DANE > on Postfix, so let's set it aside and pick that back up on the musl > list or elsewhere later.
qmail famously used a 512 byte buffer for the DNS response (the same amount that can fit into a UDP DNS response), and it wasn't enough for some MX responses at the time. Pretty much everyone using qmail eventually had to patch around this. (There were also problematic ANY queries, if I recall correctly.) DNS practices for mail have changed since then. Maybe you can get away with a 512 byte response buffer these days if you don't use DNSSEC. I don't understand your PTR example. It seems such a fringe case that people produce larger PTR responses because they add all virtual hosts to the reverse DNS zone. Sure, it happens, but not often.
