core4u.dk is a .dk domain served by 2 nameservers (elmo.ns.cloudflare.com, mckinley.ns.cloudflare.com). It was registered on 23 December 2025 (WHOIS) and was already in the .dk zone when our tracking began on 16 June 2026. Mail is handled by core4u-dk.mail.protection.outlook.com. The zone is not DNSSEC-signed, has no DMARC policy and has no IPv6 address. 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.
| Priority | TTL | Mail Server | IP addresses | PTR | ASN |
|---|---|---|---|---|---|
| 0 | 300s | core4u-dk.mail.protection.outlook.com | — | — | — |
| Service | CNAME / IP |
|---|---|
| 🔷 Autodiscover | autodiscover.outlook.com → 40.104.116.24 |
| TXT Record |
|---|
| v=spf1 include:spf.protection.outlook.com ~all |
| Policy | Record (core4u.dk) |
|---|---|
| ~all (soft fail) | v=spf1 include:spf.protection.outlook.com ~all |
| www | NXDOMAIN |
| www vs bare domain | Neither resolves core4u.dk: no address www.core4u.dk: no address |
| Wildcard | No |
| Selector | CNAME | Key |
|---|---|---|
| selector1 | selector1-core4u-dk._domainkey.core4u.a-v1.dkim.mail.microsoft | RSA · ~2048 bit |
| selector2 | selector2-core4u-dk._domainkey.core4u.a-v1.dkim.mail.microsoft | RSA · ~2048 bit |
DKIM selectors can't be listed, so we check the common ones (Microsoft 365, Google, Mailchimp, SendGrid, generic). Keys under other selectors aren't shown.
DNS lookups: 1/10 · policy: ~all
No problems found| Type | Name | Value |
|---|---|---|
| TXT | _acme-challenge.core4u.dk | cfr9Sn_cnMFJl08HYnd9a3aslnT_bUk0cxrDyOWrrNI |
| TXT | _acme-challenge.core4u.dk | v7D17CIB-4aFMUfzMuheeEWzNPWnP_HRltImj9Qvw3U |
| Check | Result |
|---|---|
| Validation Status | 🔓 Insecure |
| AD Flag (resolver validates) | ✗ Not set |
| DS Record | ✗ Not found |
| DNSKEY Record | ✗ Not found |
| Flags | resolution failed: ncache nxrrset |
| Field | Value |
|---|---|
| Serial | 2415081882 |
| Primary NS (MNAME) | elmo.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 | 2025-12-23 |
| Expires | 2026-12-22 (66d) |
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).
No other domain with this registrant in our WHOIS data yet| Scanned At | Duration | Records | DNSSEC |
|---|---|---|---|
| 2026-10-02 17:04:11 | 2165ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-09-21 22:59:37 | 1630ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-09-18 09:35:17 shown | 3257ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-09-09 07:30:23 | 1563ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-09-04 15:42:01 | 1014ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-08-28 15:38:06 | 545ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-08-27 14:46:46 | 697ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-07-21 04:09:06 | 17823ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-06-22 21:23:33 | 804ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-06-22 16:07:09 | 985ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-06-20 04:54:21 | 2007ms | 2 NS 0 A 1 MX | 🔓 Insecure |
| 2026-06-16 22:25:50 | 2368ms | 2 NS 0 A 1 MX | 🔓 Insecure |