DNS protocol tweaks

Following settings change low-level details of DNS protocol implementation. Default values should not be changed except for very special cases.

net.bufsize([udp_bufsize])

Get/set maximum EDNS payload size advertised in DNS packets. Default is 4096 bytes and the default will be lowered to value around 1220 bytes in future, once DNS Flag Day 2020 becomes effective.

Minimal value allowed by standard RFC 6891 is 512 bytes, which is equal to DNS packet size without Extension Mechanisms for DNS. Value 1220 bytes is minimum size required in DNSSEC standard RFC 4035.

Example output:

> net.bufsize(4096)
nil
> net.bufsize()
4096

Module workarounds resolver behavior on specific broken sub-domains. Currently it mainly disables case randomization.

modules.load('workarounds < iterate')