on-undervisning.dk is a .dk domain served by 2 nameservers (betty.ns.cloudflare.com, simon.ns.cloudflare.com). It was registered on 31 May 2024 (WHOIS) and was already in the .dk zone when our tracking began on 16 June 2026. Its website address 104.21.41.132 is hosted by Cloudflare, Inc. (AS13335). Mail is handled by onundervisning-dk0e.o-v1.mx.microsoft. The zone is DNSSEC-signed and validates, publishes a DMARC policy and is reachable over IPv6. Below are all of its DNS records from this scan: nameservers, A/AAAA, MX, TXT, SPF, DMARC, CAA, TLSA/DANE, MTA-STS, SRV and more.
| IP | TTL | PTR | ASN | ISP / Org | CIDR | Country | City |
|---|---|---|---|---|---|---|---|
| 104.21.41.132 | 300s | — | AS13335 | Cloudflare, Inc. | 104.21.0.0/17 | — | — |
| 172.67.147.95 | 300s | — | AS13335 | Cloudflare, Inc. | 172.67.128.0/17 | — | — |
| Service | CNAME / IP |
|---|---|
| 🔷 Autodiscover | autodiscover.outlook.com → 40.104.116.8 |
| IPv6 Address | TTL | PTR | ASN | ISP / Org | CIDR | Country | City |
|---|---|---|---|---|---|---|---|
| 2606:4700:3035::6815:2984 | 300s | — | AS13335 | Cloudflare, Inc. | 2606:4700:3000:0:0:0:0:0/42 | — | — |
| 2606:4700:3037::ac43:935f | 300s | — | AS13335 | Cloudflare, Inc. | 2606:4700:3000:0:0:0:0:0/42 | — | — |
| Priority | Target | SvcParams |
|---|---|---|
| 1 service | . | alpn="h3,h2" ipv4hint=104.21.41.132,172.67.147.95 ech=AEX+DQBBTAAgACCauk+cc3c7hdEYGHKp9jDfKiQxLE1kjlr+Bg+h14waEwAEAAEAAQASY2xvdWRmbGFyZS1lY2guY29tAAA= ipv6hint=2606:4700:3035::6815:2984,2606:4700:3037::ac43:935f |
| TXT Record |
|---|
| bw=WlGsChgQ9nxymtPHZwVThudCUCSfbyJlRwcVLoejkrtR |
| google-site-verification=k1TfhtD4axM_t8rHZVvbLoV12qWcn_3cxlf-y8KFDUc |
| MS=ms52776462 |
| v=spf1 include:_spf.google.com include:spf.protection.outlook.com include:_spf.relay.mailprotect.be -all |
| Policy | Record (on-undervisning.dk) |
|---|---|
| -all (hard fail) | v=spf1 include:_spf.google.com include:spf.protection.outlook.com include:_spf.relay.mailprotect.be -all |
| Policy | Record (_dmarc.on-undervisning.dk) |
|---|---|
| p=quarantine | v=DMARC1; p=quarantine; sp=quarantine; pct=40; rua=mailto:dmarcreports-rua@redbarnet.dk; ruf=mailto:dmarcreports-ruf@redbarnet.dk; |
| Check | Result |
|---|---|
| Status | 🧪 Testing |
| TXT record (_mta-sts) | ✓ Found |
| HTTPS policy | ✓ Valid |
| Mode | testing |
| Policy ID | 20250324162316Z |
| max_age | 604800s |
| Policy MX | onundervisning-dk0e.o-v1.mx.microsoft |
| Status | Report address (rua) |
|---|---|
| ✓ Enabled | mailto:tls-report@redbarnet.dk |
| www | 104.21.41.132 172.67.147.95 2606:4700:3035::6815:2984 2606:4700:3037::ac43:935f (AS13335) (address records, no CNAME) |
| www vs bare domain | Same network on-undervisning.dk: 104.21.41.132 172.67.147.95 2606:4700:3035::6815:2984 2606:4700:3037::ac43:935f (AS13335) www.on-undervisning.dk: 104.21.41.132 172.67.147.95 2606:4700:3035::6815:2984 2606:4700:3037::ac43:935f (AS13335) |
| Wildcard | No |
| Denial of existence | Compact NSEC (RFC 9824, "black lies") not walkable |
| CDS / CDNSKEY | Published: key rollovers can be automated with the registry (RFC 7344/8078) 1 CDS, 1 CDNSKEY |
DNS lookups: 4/10 · policy: -all
No problems found| Service / Owner | Type | Cert association |
|---|---|---|
| SMTP _25._tcp.onundervisning-dk0e.o-v1.mx.microsoft | DANE-EE · SPKI · SHA-256 | 54883CC5F1849331E6BF5002C3129D20… |
| SMTP _25._tcp.onundervisning-dk0e.o-v1.mx.microsoft | DANE-TA · Full cert · SHA-256 | EA7A25255D111FC3CE4CB8FABE3ADF9C… |
| SMTP _25._tcp.onundervisning-dk0e.o-v1.mx.microsoft | DANE-EE · SPKI · SHA-256 | 803F7447CC75B208DBCA042346F5D8DF… |
| SMTP _25._tcp.onundervisning-dk0e.o-v1.mx.microsoft | DANE-TA · Full cert · SHA-256 | C1AD7778796D20BCA65C889A26550211… |
| Check | Result |
|---|---|
| Validation Status | 🔒 Secure |
| AD Flag (resolver validates) | ✓ Set |
| DS Record | ✓ Found |
| DNSKEY Record | ✓ Found |
| Flags | fully validated |
| Field | Value |
|---|---|
| Serial | 2413346647 |
| Primary NS (MNAME) | betty.ns.cloudflare.com |
| Responsible (RNAME) | dns@cloudflare.com |
| Refresh | 10000s |
| Retry | 2400s |
| Expire | 604800s |
| Minimum (neg-cache TTL) | 1800s |
| Field | Value |
|---|---|
| Registrar | Punktum dk A/S (direct) |
| Registered | 2024-05-31 |
| Expires | 2027-05-30 (220d) |
Other .dk domains whose WHOIS registrant has the same name and postal address. Matched on a keyed hash: the registrant's details are not stored or shown. Covers only domains whose WHOIS we have fetched (refreshed about monthly).
| Scanned At | Duration | Records | DNSSEC |
|---|---|---|---|
| 2026-10-21 05:12:19 | 859ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-09-30 09:14:37 | 1033ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-09-29 09:03:11 | 999ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-09-28 08:36:33 | 1051ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-09-08 23:27:20 | 2608ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-09-01 14:44:06 | 1451ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-08-28 17:22:38 shown | 2541ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-08-13 12:50:57 | 1442ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-08-02 14:50:05 | 9351ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-07-20 11:59:07 | 1562ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-07-10 13:15:16 | 2481ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-07-02 20:05:27 | 12221ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-06-26 14:23:03 | 1354ms | 2 NS 2 A 1 MX | 🔒 Secure |
| 2026-06-24 01:28:44 | 1841ms | 2 NS 4 A 1 MX | 🔒 Secure |
| 2026-06-18 03:05:27 | 1328ms | 2 NS 4 A 1 MX | 🔒 Secure |