Bad firewall/nameserver behaviour causing timeouts of DNS queries.

The following nameservers for Alexa top 1M names fail to respond
to EDNS queries with EDNS options specified or fail to respond to
consecutive EDNS queries. These have been run through the checks
multiple times to reduce the probability of false positives as
timeout can be the due to multiple causes.

For many there are other errors that should also be addressed.

This misbehaviour can cause DNSSEC validation to FAIL when the
servers serve signed zones.

This misbehaviour does result in significantly slower DNS resolution
(multiple seconds).

You can test your servers at

This is sent here because both SOA and whois contact details are
wrong too often to bother trying to send to these addresses even
if whois was easy to parse.

Please fix your firewalls / nameservers as they are causing operational