Generated: 2026-09-27T00:00:01Z -- 2026-09-27T07:46:32Z
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:
76633 of 77442 (98.96%) responded to a EDNS version 0 query
76614 of 77442 (98.93%) responded to a EDNS unknown option
76614 of 77442 (98.93%) responded to a EDNS unknown flags
76526 of 77442 (98.82%) responded to a EDNS version 1 query
76499 of 77442 (98.78%) responded to a EDNS unknown version and option
75830 of 77442 (97.92%) of nameservers support EDNS
3692 of 75830 (4.87%) EDNS capable servers are all ok
73857 of 75830 (97.40%) EDNS capable servers support unknown EDNS versions
74797 of 75830 (98.64%) EDNS capable servers support unknown EDNS options
74891 of 75830 (98.76%) EDNS capable servers support unknown EDNS flags
73679 of 75830 (97.16%) EDNS capable servers support unknown EDNS version and options
75364 of 75830 (99.39%) EDNS capable servers support DO=1
32643 of 75830 (43.05%) EDNS capable servers return a NSID option
29599 of 75830 (39.03%) EDNS capable servers return a EXPIRE option
46778 of 75830 (61.69%) EDNS capable servers return a SUBNET option
27920 of 75830 (36.82%) EDNS capable servers return a Server EDNS COOKIE option
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