🛡️ Nameserver Resilience

Domains whose DNS hangs on a single nameserver, address, network or AS · all insights

DNS should never hang on one server. This page counts the .dk domains whose nameservers share a single host, address, network or autonomous system, the single points of failure that turn one outage into a dead domain. Data comes from our own scanners, which re-resolve every .dk domain in the zone roughly once a week.

🛡️ Single points of failure

1,182,584 working delegations with resolvable nameservers (lame excluded)
Every nameserver is on…DomainsShareWhy it matters
A single nameserver host1490.01%Any outage or mistake on that host takes the domain offline; RFC 1034 asks for at least two.
A single nameserver address1,3040.11%Several NS names, but they all resolve to one IP, so they are really one server.
One IPv4 /24 and no IPv610,6830.90%All nameservers share one network: a routing problem there takes them all down.
One autonomous system757,07664.0%Common and usually fine with a large provider, but one network outage still takes all nameservers down.
No IPv6 nameserver85,2097.2%IPv6-only resolvers cannot reach the zone.

Click a row to list its domains (computed 2026-10-03 04:10).

📋 One autonomous system

757,076 domains
DomainNameservers and addresses
a-frim.dkns.gpserver.dk 65.21.48.197 AS24940
ns2.gpserver.com 195.201.149.111 AS24940
a-furesoe.dkns3.nordicway.dk 2a01:4f8:c2c:d3c0::1 AS24940, 78.47.45.64 AS24940
ns4.nordicway.dk 2a01:4f8:c010:24a2::1 AS24940, 78.47.56.84 AS24940
a-fys-sport.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-fysonline.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-g-p.dkns1.curanet.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.curanet.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-g.dkns1.curanet.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.curanet.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-gain.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-gainer.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-galleri.dkns4.dns-123.net 35.198.132.83 AS396982
ns5.dns-123.net 35.187.184.173 AS396982
ns6.dns-123.net 35.228.54.1 AS396982
a-gartner.dkns1.curanet.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.curanet.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-gift-from-heaven.dkfiona.ns.cloudflare.com 108.162.192.157 AS13335, 172.64.32.157 AS13335, 173.245.58.157 AS13335, 2606:4700:50::adf5:3a9d AS13335, 2803:f800:50::6ca2:c09d AS13335, 2a06:98c1:50::ac40:209d AS13335
rob.ns.cloudflare.com 108.162.193.140 AS13335, 172.64.33.140 AS13335, 173.245.59.140 AS13335, 2606:4700:58::adf5:3b8c AS13335, 2803:f800:50::6ca2:c18c AS13335, 2a06:98c1:50::ac40:218c AS13335
a-group.dkns3.nordicway.dk 2a01:4f8:c2c:d3c0::1 AS24940, 78.47.45.64 AS24940
ns4.nordicway.dk 2a01:4f8:c010:24a2::1 AS24940, 78.47.56.84 AS24940
a-gruppen.dkns4.dns-123.net 35.198.132.83 AS396982
ns5.dns-123.net 35.187.184.173 AS396982
ns6.dns-123.net 35.228.54.1 AS396982
a-guldborgsund.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-h-b.dkns.scannet2.dk 185.25.141.9 AS48854, 2a02:2339:4006:10d::4171:4171 AS48854
ns2.scannet2.dk 2a02:2339:1:112:0:5:1:b11 AS48854, 91.197.248.72 AS48854
a-h-consulting.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-h.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-ha.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-hasselbalch.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
a-hassenkam.dkjoel.ns.cloudflare.com 108.162.193.184 AS13335, 172.64.33.184 AS13335, 173.245.59.184 AS13335, 2606:4700:58::adf5:3bb8 AS13335, 2803:f800:50::6ca2:c1b8 AS13335, 2a06:98c1:50::ac40:21b8 AS13335
lina.ns.cloudflare.com 108.162.192.187 AS13335, 172.64.32.187 AS13335, 173.245.58.187 AS13335, 2606:4700:50::adf5:3abb AS13335, 2803:f800:50::6ca2:c0bb AS13335, 2a06:98c1:50::ac40:20bb AS13335
a-haveanlaeg.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
a-hbyg.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
a-hereford-beefstouw.dkns.scannet2.dk 185.25.141.9 AS48854, 2a02:2339:4006:10d::4171:4171 AS48854
ns2.scannet2.dk 2a02:2339:1:112:0:5:1:b11 AS48854, 91.197.248.72 AS48854
a-hoejfeldt.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-hold.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
a-holdet.dkns1-04.azure-dns.com 13.107.236.4 AS8075, 2603:1061:0:700::4 AS8075
ns2-04.azure-dns.net 150.171.21.4 AS8075, 2620:1ec:8ec:700::4 AS8075
ns3-04.azure-dns.org 204.14.183.4 AS8075, 2a01:111:4000:700::4 AS8075
ns4-04.azure-dns.info 208.84.5.4 AS8075, 2620:1ec:bda:700::4 AS8075
a-horse.dkns1.curanet.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.curanet.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-host.dkns1.centos-webpanel.com 54.36.136.192 AS16276
ns2.centos-webpanel.com 198.27.104.41 AS16276
a-hotel.dkns1.curanet.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.curanet.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-hs.dkns1.designrus.dk 176.9.4.22 AS24940, 2a01:4f8:141:3416::2 AS24940
ns2.designrus.dk 2a01:4f8:242:5649::2 AS24940, 49.12.124.182 AS24940
a-hvidevare.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-hvidevarer.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-højfeldt.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-i.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-j.dkns1.nhl-data.dk 185.136.96.11 AS203391, 2a06:fb00:1::1:11 AS203391
ns2.nhl-data.dk 185.136.97.11 AS203391, 2a06:fb00:1::2:11 AS203391
ns3.nhl-data.dk 185.136.98.11 AS203391, 2a06:fb00:1::3:11 AS203391
ns4.nhl-data.dk 185.136.99.11 AS203391, 2a06:fb00:1::4:11 AS203391
a-jensen.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
a-job.dkdahlia.ns.cloudflare.com 108.162.192.89 AS13335, 172.64.32.89 AS13335, 173.245.58.89 AS13335, 2606:4700:50::adf5:3a59 AS13335, 2803:f800:50::6ca2:c059 AS13335, 2a06:98c1:50::ac40:2059 AS13335
margo.ns.cloudflare.com 108.162.195.144 AS13335, 162.159.44.144 AS13335, 172.64.35.144 AS13335, 2606:4700:58::a29f:2c90 AS13335, 2803:f800:50::6ca2:c390 AS13335, 2a06:98c1:50::ac40:2390 AS13335
a-jorgensen-eftf.dkns1.curanet.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.curanet.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-jorgensen.dkns1.dnsserver.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.dnsserver.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-jour.dkns1.shellhost.dk 193.200.90.91 AS62121, 2001:67c:564::13 AS62121
ns2.shellhost.dk 193.200.91.90 AS62121
a-journey.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-k-s.dkns1.eurodns.com 199.167.66.107 AS23393, 2610:1c8:b002::107 AS23393
ns2.eurodns.com 104.37.178.107 AS23393, 2610:1c8:b001::107 AS23393
ns3.eurodns.com 199.167.66.108 AS23393, 2610:1c8:b002::108 AS23393
ns4.eurodns.com 104.37.178.108 AS23393, 2610:1c8:b001::108 AS23393
a-k.dkns1.simpleagencygroup.dk 185.25.141.12 AS48854, 2a02:2339:4006:108::123 AS48854
ns2.simpleagencygroup.dk 2a02:2339:1:10f::123:123 AS48854, 91.197.248.75 AS48854
a-kalundborg.dkns4.dns-123.net 35.198.132.83 AS396982
ns5.dns-123.net 35.187.184.173 AS396982
ns6.dns-123.net 35.228.54.1 AS396982
a-kampe.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-kasse-dk.dkandy.ns.cloudflare.com 108.162.193.101 AS13335, 172.64.33.101 AS13335, 173.245.59.101 AS13335, 2606:4700:58::adf5:3b65 AS13335, 2803:f800:50::6ca2:c165 AS13335, 2a06:98c1:50::ac40:2165 AS13335
tess.ns.cloudflare.com 108.162.192.227 AS13335, 172.64.32.227 AS13335, 173.245.58.227 AS13335, 2606:4700:50::adf5:3ae3 AS13335, 2803:f800:50::6ca2:c0e3 AS13335, 2a06:98c1:50::ac40:20e3 AS13335
a-kasse-forsikring.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-kasse-guiden.dkns1.simply.com 2a02:2339:1:15c::4562:4562 AS48854, 91.197.248.78 AS48854
ns2.simply.com 185.25.141.15 AS48854, 2a02:2339:4006:101::4562:4562 AS48854
ns3.simply.com 91.197.248.79 AS48854
ns4.simply.com 91.197.248.80 AS48854
a-kasse-portalen.dkns.dandomain.dk 185.25.141.3 AS48854, 2a02:2339:4006:109::dd AS48854
ns2.dandomain.dk 2a02:2339:1:108::dd:dd AS48854, 91.197.248.66 AS48854
a-kasse-priser.dknoel.ns.cloudflare.com 108.162.193.216 AS13335, 172.64.33.216 AS13335, 173.245.59.216 AS13335, 2606:4700:58::adf5:3bd8 AS13335, 2803:f800:50::6ca2:c1d8 AS13335, 2a06:98c1:50::ac40:21d8 AS13335
ulla.ns.cloudflare.com 108.162.192.233 AS13335, 172.64.32.233 AS13335, 173.245.58.233 AS13335, 2606:4700:50::adf5:3ae9 AS13335, 2803:f800:50::6ca2:c0e9 AS13335, 2a06:98c1:50::ac40:20e9 AS13335
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