This page lists every .dk domain whose delegation includes the nameserver auth1.dns.cogentco.com, together with its IP addresses, network, zone-transfer and ANY-query behaviour, the protocols and RFCs it supports (TCP, EDNS, cookies, NSID, DNS over TLS/HTTPS …), the nameserver sets it is used in and how fast those sets answer. Use it to size a DNS provider, audit a migration or find domains still pointing at an old server. Data comes from our own scanners, which re-resolve every .dk domain in the zone roughly once a week.
The nameserver auth1.dns.cogentco.com appears in the delegation of 1 .dk domain in our dataset — <0.01% of every scanned .dk domain. The full list is below — here is how those domains look under the hood.
On the DNSSEC side, 0 (0.0%) validate as secure — below the zone-wide average of 63.9%, while 1 (100.0%) are unsigned, with none failing validation outright.
Delegation health looks clean, too: none of these domains currently register as lame delegations at this nameserver.
Response time: across 1 timed domains, our resolver needed 148 ms on average to answer an A query and 130 ms for an NS query. Per nameserver set below.
Not profiled: it did not answer authoritatively for the zones we asked it about. Retried every few days.
| Nameserver set | Domains | Avg response (A) | NS lookup |
|---|---|---|---|
| auth1.dns.cogentco.com · auth2.dns.cogentco.com · cbru.br.ns.els-gms.att.net · cmtu.mt.ns.els-gms.att.net · nsa.ups.com · nsb.ups.com | 1 | 148 ms | 130 ms |
Times are the scanner's own lookups through its resolver on each domain's latest scan, so they include resolver overhead; compare sets with each other rather than reading them as raw authoritative round-trip times.
| Reverse zone | Prefix | Prefixes | Checked |
|---|---|---|---|
| 181.38.in-addr.arpa | 38.181.0.0/16 | 3 | 2026-10-18 |
| 161.63.in-addr.arpa | 63.161.0.0/16 | 2 | 2026-10-17 |
| 175.63.in-addr.arpa | 63.175.0.0/16 | 2 | 2026-10-17 |
| 2.153.in-addr.arpa | 153.2.0.0/16 | 2 | 2026-10-17 |
| 255.38.in-addr.arpa | 38.255.0.0/16 | 2 | 2026-10-20 |
| 0.11.149.in-addr.arpa | 149.11.0.0/24 | 1 | 2026-10-13 |
| 0.137.83.in-addr.arpa | 83.137.0.0/24 | 1 | 2026-10-17 |
| 1.137.83.in-addr.arpa | 83.137.1.0/24 | 1 | 2026-10-16 |
| 105.13.185.in-addr.arpa | 185.13.105.0/24 | 1 | 2026-10-16 |
| 117.38.in-addr.arpa | 38.117.0.0/16 | 1 | 2026-10-20 |
| 128.43.154.in-addr.arpa | 154.43.128.0/24 | 1 | 2026-10-15 |
| 143.236.206.in-addr.arpa | 206.236.143.0/24 | 1 | 2026-10-16 |
| 175.208.91.in-addr.arpa | 91.208.175.0/24 | 1 | 2026-10-19 |
| 180.38.in-addr.arpa | 38.180.0.0/16 | 1 | 2026-10-19 |
| 180.44.154.in-addr.arpa | 154.44.180.0/24 | 1 | 2026-10-20 |
| 22.149.in-addr.arpa | 149.22.0.0/16 | 1 | 2026-10-16 |
| 220.46.38.in-addr.arpa | 38.46.220.0/24 | 1 | 2026-10-19 |
| 221.46.38.in-addr.arpa | 38.46.221.0/24 | 1 | 2026-10-16 |
| 236.206.in-addr.arpa | 206.236.0.0/16 | 1 | 2026-10-20 |
| 48.119.38.in-addr.arpa | 38.119.48.0/24 | 1 | 2026-10-20 |
| 5.149.in-addr.arpa | 149.5.0.0/16 | 1 | 2026-10-16 |
| 55.119.38.in-addr.arpa | 38.119.55.0/24 | 1 | 2026-10-16 |
| 62.154.in-addr.arpa | 154.62.0.0/16 | 1 | 2026-10-19 |
| 66.77.80.in-addr.arpa | 80.77.66.0/24 | 1 | 2026-10-16 |
| 75.166.63.in-addr.arpa | 63.166.75.0/24 | 1 | 2026-10-16 |
| 76.11.149.in-addr.arpa | 149.11.76.0/24 | 1 | 2026-10-16 |
| 90.38.in-addr.arpa | 38.90.0.0/16 | 1 | 2026-10-18 |
in-addr.arpa / ip6.arpa zones delegated to auth1.dns.cogentco.com, found from the SOA of the reverse name of each IPv4 /24 behind the zone's websites (and any CIDR page viewed), so the zone is the real delegation point, at whatever prefix length it sits. A /24 whose reverse delegation is broken (SERVFAIL) is not credited to anyone.
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