checksum.dk

📜 Historical scan 2026-09-05 07:43:29 · ← Latest scan

⬇ Zone File 📜 Timeline & History ⚡ Scan Now

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 this scan: nameservers, A/AAAA, MX, TXT, SPF, DMARC, CAA, TLSA/DANE, MTA-STS, SRV and more.

🖥️ Nameservers#

2 records 38ms

Nameserver	IP addresses	PTR	ASN / ISP
aron.ns.cloudflare.com	108.162.192.69 172.64.32.69 173.245.58.69 2606:4700:50::adf5:3a45 2803:f800:50::6ca2:c045 2a06:98c1:50::ac40:2045	aron.ns.cloudflare.com aron.ns.cloudflare.com aron.ns.cloudflare.com aron.ns.cloudflare.com aron.ns.cloudflare.com aron.ns.cloudflare.com	AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc.
conrad.ns.cloudflare.com	108.162.195.146 162.159.44.146 172.64.35.146 2606:4700:58::a29f:2c92 2803:f800:50::6ca2:c392 2a06:98c1:50::ac40:2392	conrad.ns.cloudflare.com conrad.ns.cloudflare.com conrad.ns.cloudflare.com conrad.ns.cloudflare.com conrad.ns.cloudflare.com conrad.ns.cloudflare.com	AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc.

🌍 A Records#

2 records 33ms

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	—	—

📧 MX Records#

3 records 34ms

Priority	TTL	Mail Server	IP addresses	PTR	ASN
70	300s	route1.mx.cloudflare.net	162.159.205.11 162.159.205.12 162.159.205.13 2606:4700:f5::b 2606:4700:f5::c 2606:4700:f5::d	route1.mx.cloudflare.net route1.mx.cloudflare.net route1.mx.cloudflare.net route1.mx.cloudflare.net route1.mx.cloudflare.net route1.mx.cloudflare.net	AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc.
73	300s	route2.mx.cloudflare.net	162.159.205.17 162.159.205.18 162.159.205.19 2606:4700:f5::10 2606:4700:f5::e 2606:4700:f5::f	route2.mx.cloudflare.net route2.mx.cloudflare.net route2.mx.cloudflare.net route2.mx.cloudflare.net route2.mx.cloudflare.net route2.mx.cloudflare.net	AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc.
93	300s	route3.mx.cloudflare.net	162.159.205.23 162.159.205.24 162.159.205.25 2606:4700:f5::11 2606:4700:f5::12 2606:4700:f5::13	route3.mx.cloudflare.net route3.mx.cloudflare.net route3.mx.cloudflare.net route3.mx.cloudflare.net route3.mx.cloudflare.net route3.mx.cloudflare.net	AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc.

🔷 AAAA Records (IPv6)#

2 records 28ms

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	—	—

🔐 HTTPS Records#

1 records 27ms

Priority	Target	SvcParams
1 service	.	alpn="h3,h2" ipv4hint=104.21.41.243,172.67.167.207 ech=AEX+DQBBRwAgACCAiA+cQZhezuCQ6EWdjsRfwN3rV32F5sm+xew5p/syYgAEAAEAAQASY2xvdWRmbGFyZS1lY2guY29tAAA= ipv6hint=2606:4700:3031::ac43:a7cf,2606:4700:3037::6815:29f3

📝 TXT Records#

1 records 159ms

TXT Record
v=spf1 include:_spf.mx.cloudflare.net ~all

✉️ SPF#

Policy	Record (checksum.dk)
~all (soft fail)	v=spf1 include:_spf.mx.cloudflare.net ~all

📨 DMARC#

Policy	Record (_dmarc.checksum.dk)
p=reject	v=DMARC1; p=reject; sp=reject; adkim=s; aspf=s; rua=mailto:a5dd465d7989486180e756a2ddb6b8f4@dmarc-reports.cloudflare.net;

📬 MTA-STS#

✗ No MTA-STS policy — SMTP TLS not enforced

📈 TLSRPT#

✗ No TLSRPT record — no SMTP TLS failure reporting

📜 CAA Records#

✗ No CAA records — any CA may issue certificates

🧩 Web & zone#

latest probe, not this scan · checked 2026-10-07 17:02:19

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

✍️ DKIM keys#

6 found

Selector	CNAME	Key
default	—	Revoked (empty key)
dkim	—	Revoked (empty key)
k1	—	Revoked (empty key)
mail	—	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.

🔎 SPF check#

zone-wide SPF report

DNS lookups: 1/10 · policy: ~all

No problems found

🔏 ACME Challenge#

Type	Name	Value
TXT	_acme-challenge.checksum.dk	l7qQTG7i_WHQhWGPQQAPHXWHRFKKbmp_OEBMygAWUpk
TXT	_acme-challenge.checksum.dk	slqXFoWM7jvfrP_w3MmNE8EAU1gAn1xO7b_3eRQuJ_U

🔗 TLSA / DANE#

9 records 57ms

Service / Owner	Type	Cert association
SMTP _25._tcp.route1.mx.cloudflare.net	DANE-EE · SPKI · SHA-256	0F0C6C164A36F97E7B4C5A5B69D6F4F2…
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.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…

🔐 DNSSEC#

112ms

Check	Result
Validation Status	🔓 Insecure
AD Flag (resolver validates)	✗ Not set
DS Record	✗ Not found
DNSKEY Record	✓ Found
Flags	unsigned answer

🏷️ SOA#

0ms

Field	Value
Serial	2414002236
Primary NS (MNAME)	aron.ns.cloudflare.com
Responsible (RNAME)	dns@cloudflare.com
Refresh	10000s
Retry	2400s
Expire	604800s
Minimum (neg-cache TTL)	1800s

📋 Registration#

WHOIS fetched 2026-10-13 23:42:09

Field	Value
Registrar	Simply.com A/S
Registered	1999-07-06
Expires	2027-09-30 (344d)

🔗 Same registrant#

1 domain

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

📋 WHOIS#

⏱️ Lookup Timing#

38ms

33ms

34ms

AAAA

28ms

TXT

159ms

CAA

30ms

HTTPS

27ms

TLSA

57ms

SOA

0ms

MTA-STS

55ms

DNSSEC

112ms

SRV

71ms

Total

896ms

🕐 Scan History#

Scanned At	Duration	Records	DNSSEC
2026-10-07 17:02:19	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 shown	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