The other thing it could be is broken PMTUD / failure fragment at network MTU. We defined socket options to do this 2 decades ago.
-- Mark Andrews > On 9 Nov 2023, at 06:00, Matthew Pounsett <m...@conundrum.com> wrote: > > On Wed, Nov 8, 2023 at 2:12 AM Bryan Fields <br...@bryanfields.net> wrote: >> >> >> Could these be related to the fact that dnsvis.net is trying to reach these >> servers via IPv6 and I think they use Hurricane for transit. Since HE and >> Cogent is a major gap, this causes them to time out trying to reach the C >> root >> server over IPv6. > > We have a tunnel set up to allow DNSViz to reach C-root, however > anything else single-homed on Cogent is unreachable to DNSViz via > IPv6.
