Generated: 2026-07-26T00:00:01Z -- 2026-07-26T09:32:15Z
The following report was generated automatically.
Packet loss and network issues may have introduced false positives.
Please verify the results before taking action.
You can report issues with this report to: marka@isc.org
Most recursive resolvers now support EDNS. Lack of EDNS support in authoritative servers results in additional queries being made as the recursive servers need to retry with plain DNS and results in slower DNS resolution.
Not answering EDNS queries is particularly bad as that is indistingishable from packet loss.
Incorrect EDNS behaviour when presented with unknown EDNS versions and EDNS options can result in DNS resolution failures and/or DNSSEC validation failures.
Failure to run fully EDNS compliant nameservers will make it hard to deploy developments like DNS COOKIES which provides mitigation against DNS amplification attacks, off path spoofing resistance, RRL advoidance and excessive resource usage.
ok - test passed.
badvers - BADVERS returned.
badversion - expected EDNS version not found.
echoed - EDNS option echoed back.
formerr - FORMERR returned.
mbz - EDNS flags echoed back.
nodo - EDNS DO flag not echoed.
noopt - OPT record not found when expected.
nosoa - SOA not found when expected.
notimp - NOTIMP returned.
refused - REFUSED returned.
servfail - SERVFAIL returned.
soa - SOA found when not expected.
status - expected status code not found.
toobig - UDP response bigger that advertised buffer size.
version - expected EDNS version not found.
reset - TCP connection reset.
timeout - lookup timed out.
Of servers that responded at all:
76004 of 77156 (98.51%) responded to a EDNS version 0 query
75962 of 77156 (98.45%) responded to a EDNS unknown option
75969 of 77156 (98.46%) responded to a EDNS unknown flags
75895 of 77156 (98.37%) responded to a EDNS version 1 query
75852 of 77156 (98.31%) responded to a EDNS unknown version and option
75101 of 77156 (97.34%) of nameservers support EDNS
3650 of 75101 (4.86%) EDNS capable servers are all ok
72897 of 75101 (97.07%) EDNS capable servers support unknown EDNS versions
74028 of 75101 (98.57%) EDNS capable servers support unknown EDNS options
74122 of 75101 (98.70%) EDNS capable servers support unknown EDNS flags
72706 of 75101 (96.81%) EDNS capable servers support unknown EDNS version and options
74629 of 75101 (99.37%) EDNS capable servers support DO=1
31964 of 75101 (42.56%) EDNS capable servers return a NSID option
29424 of 75101 (39.18%) EDNS capable servers return a EXPIRE option
46227 of 75101 (61.55%) EDNS capable servers return a SUBNET option
27605 of 75101 (36.76%) EDNS capable servers return a Server EDNS COOKIE option
© 2026 Internet Systems Consortium