[ratelimits] NXDOMAINS rate-limited despite nxdomains-per-second set to 0

[Anand Buddhdev]

Hi,

Yesterday I enabled the rate-limit patch on our BIND servers, with the
following configuration:

rate-limit {
              responses-per-second 10;
              nxdomains-per-second 0;
              max-table-size 40000;
};

However, I noticed the following in our log files:

rate-limit: limiting NXDOMAIN responses to x.x.x.x/24 for IN PTR
111.in-addr.arpa

It looks like the rate-limit was still being applied to NXDOMAIN
responses. Is this a bug?

$ named -v
BIND 9.9.1-vjs197.15-P3

Anand Buddhdev
RIPE NCC