checksum.dk is a .dk domain served by 2 nameservers (aron.ns.cloudflare.com, conrad.ns.cloudflare.com). It was registered on 6 July 1999 (WHOIS) and was already in the .dk zone when our tracking began on 16 June 2026. Its website address 104.21.41.243 is hosted by Cloudflare, Inc. (AS13335). Mail is handled by route1.mx.cloudflare.net, route2.mx.cloudflare.net and 1 more. The zone is not DNSSEC-signed, publishes a DMARC policy and is reachable over IPv6. Below are all of its DNS records from our latest 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 |
|---|---|---|---|---|---|---|---|
| 104.21.41.243 | 300s | — | AS13335 | Cloudflare, Inc. | 104.21.0.0/17 | — | — |
| 172.67.167.207 | 300s | — | AS13335 | Cloudflare, Inc. | 172.67.128.0/17 | — | — |
| IPv6 Address | TTL | PTR | ASN | ISP / Org | CIDR | Country | City |
|---|---|---|---|---|---|---|---|
| 2606:4700:3031::ac43:a7cf | 300s | — | AS13335 | Cloudflare, Inc. | 2606:4700:3000:0:0:0:0:0/42 | — | — |
| 2606:4700:3037::6815:29f3 | 300s | — | AS13335 | Cloudflare, Inc. | 2606:4700:3000:0:0:0:0:0/42 | — | — |
| Priority | Target | SvcParams |
|---|---|---|
| 1 service | . | alpn="h3,h2" ipv4hint=104.21.41.243,172.67.167.207 ech=AEX+DQBB3gAgACBHVblYM9zKIwnPfx3QE5uLVPlY+jEtl3cUO/CUU2z+EAAEAAEAAQASY2xvdWRmbGFyZS1lY2guY29tAAA= ipv6hint=2606:4700:3031::ac43:a7cf,2606:4700:3037::6815:29f3 |
| TXT Record |
|---|
| v=spf1 include:_spf.mx.cloudflare.net ~all |
| Policy | Record (checksum.dk) |
|---|---|
| ~all (soft fail) | v=spf1 include:_spf.mx.cloudflare.net ~all |
| Policy | Record (_dmarc.checksum.dk) |
|---|---|
| p=reject | v=DMARC1; p=reject; sp=reject; adkim=s; aspf=s; rua=mailto:a5dd465d7989486180e756a2ddb6b8f4@dmarc-reports.cloudflare.net; |
| www | 104.21.41.243 172.67.167.207 2606:4700:3031::ac43:a7cf 2606:4700:3037::6815:29f3 (AS13335) (address records, no CNAME) |
| www vs bare domain | Same network checksum.dk: 104.21.41.243 172.67.167.207 2606:4700:3031::ac43:a7cf 2606:4700:3037::6815:29f3 (AS13335) www.checksum.dk: 104.21.41.243 172.67.167.207 2606:4700:3031::ac43:a7cf 2606:4700:3037::6815:29f3 (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 |
| Selector | CNAME | Key |
|---|---|---|
| default | — | Revoked (empty key) |
| dkim | — | Revoked (empty key) |
| k1 | — | Revoked (empty key) |
| — | Revoked (empty key) | |
| s1 | — | Revoked (empty key) |
| s2 | — | Revoked (empty key) |
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| Service / Owner | Type | Cert association |
|---|---|---|
| SMTP _25._tcp.route1.mx.cloudflare.net | DANE-EE · SPKI · SHA-256 | 9BE5B7D47F9EFF930C11EB04D27CAE6B… |
| SMTP _25._tcp.route1.mx.cloudflare.net | DANE-TA · SPKI · SHA-256 | 59E738E674221702AF1EDB87C5200C1A… |
| SMTP _25._tcp.route1.mx.cloudflare.net | DANE-EE · SPKI · SHA-256 | 0F0C6C164A36F97E7B4C5A5B69D6F4F2… |
| SMTP _25._tcp.route2.mx.cloudflare.net | DANE-EE · SPKI · SHA-256 | 0F0C6C164A36F97E7B4C5A5B69D6F4F2… |
| SMTP _25._tcp.route2.mx.cloudflare.net | DANE-EE · SPKI · SHA-256 | 9BE5B7D47F9EFF930C11EB04D27CAE6B… |
| SMTP _25._tcp.route2.mx.cloudflare.net | DANE-TA · SPKI · SHA-256 | 59E738E674221702AF1EDB87C5200C1A… |
| SMTP _25._tcp.route3.mx.cloudflare.net | DANE-EE · SPKI · SHA-256 | 9BE5B7D47F9EFF930C11EB04D27CAE6B… |
| SMTP _25._tcp.route3.mx.cloudflare.net | DANE-TA · SPKI · SHA-256 | 59E738E674221702AF1EDB87C5200C1A… |
| SMTP _25._tcp.route3.mx.cloudflare.net | DANE-EE · SPKI · SHA-256 | 0F0C6C164A36F97E7B4C5A5B69D6F4F2… |
| Check | Result |
|---|---|
| Validation Status | 🔓 Insecure |
| AD Flag (resolver validates) | ✗ Not set |
| DS Record | ✗ Not found |
| DNSKEY Record | ✓ Found |
| Flags | unsigned answer |
| Field | Value |
|---|---|
| Serial | 2416073607 |
| Primary NS (MNAME) | aron.ns.cloudflare.com |
| Responsible (RNAME) | dns@cloudflare.com |
| Refresh | 10000s |
| Retry | 2400s |
| Expire | 604800s |
| Minimum (neg-cache TTL) | 1800s |
| Field | Value |
|---|---|
| Registrar | Simply.com A/S |
| Registered | 1999-07-06 |
| Expires | 2027-09-30 (344d) |
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).
| Domain | Registrar |
|---|---|
| neoncity.dk | Simply.com A/S |
| Scanned At | Duration | Records | DNSSEC |
|---|---|---|---|
| 2026-10-07 17:02:19 shown | 780ms | 2 NS 2 A 3 MX | 🔓 Insecure |
| 2026-09-28 23:23:04 | 2696ms | 2 NS 2 A 3 MX | 🔓 Insecure |
| 2026-09-27 23:16:20 | 874ms | 2 NS 2 A 3 MX | 🔓 Insecure |
| 2026-09-08 02:53:01 | 1370ms | 2 NS 2 A 3 MX | 🔓 Insecure |
| 2026-09-05 07:43:29 | 896ms | 2 NS 2 A 3 MX | 🔓 Insecure |
| 2026-08-28 03:40:52 | 9512ms | 3 NS 1 A 0 MX | 🔓 Insecure |
| 2026-08-18 09:49:53 | 605ms | 3 NS 1 A 0 MX | 🔓 Insecure |
| 2026-08-13 04:58:19 | 2062ms | 3 NS 0 A 0 MX | 🔓 Insecure |
| 2026-06-25 04:28:30 | 693ms | 2 NS 1 A 4 MX | 🔒 Secure |
| 2026-06-16 20:25:52 | 2775ms | 2 NS 1 A 4 MX | 🔒 Secure |