c-system.dk

📜 Historical scan 2026-08-23 00:20:58 · ← Latest scan

⬇ Zone File 📜 Timeline & History ⚡ Scan Now

c-system.dk is a .dk domain served by 2 nameservers (autumn.ns.cloudflare.com, gabriel.ns.cloudflare.com). It was registered on 29 October 2002 (WHOIS) and was already in the .dk zone when our tracking began on 16 June 2026. Its website address 104.21.85.94 is hosted by Cloudflare, Inc. (AS13335). Mail is handled by csystem-dk0c.mail.protection.outlook.com. 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.

🖥️ Nameservers#

2 records 343ms

Nameserver	IP addresses	PTR	ASN / ISP
autumn.ns.cloudflare.com	108.162.194.148 162.159.38.148 172.64.34.148 2606:4700:50::a29f:2694 2803:f800:50::6ca2:c294 2a06:98c1:50::ac40:2294	autumn.ns.cloudflare.com autumn.ns.cloudflare.com autumn.ns.cloudflare.com autumn.ns.cloudflare.com autumn.ns.cloudflare.com autumn.ns.cloudflare.com	AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc. AS13335 Cloudflare, Inc.
gabriel.ns.cloudflare.com	108.162.195.244 162.159.44.244 172.64.35.244 2606:4700:58::a29f:2cf4 2803:f800:50::6ca2:c3f4 2a06:98c1:50::ac40:23f4	gabriel.ns.cloudflare.com gabriel.ns.cloudflare.com gabriel.ns.cloudflare.com gabriel.ns.cloudflare.com gabriel.ns.cloudflare.com gabriel.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 306ms

IP	TTL	PTR	ASN	ISP / Org	CIDR	Country	City
104.21.85.94	300s	—	AS13335	Cloudflare, Inc.	104.21.0.0/17	—	—
172.67.204.64	300s	—	AS13335	Cloudflare, Inc.	172.67.128.0/17	—	—

📧 MX Records#

1 records 281ms

Priority	TTL	Mail Server	IP addresses	PTR	ASN
0	3600s	csystem-dk0c.mail.protection.outlook.com	2a01:111:f403:ca04::9 2a01:111:f403:ca04::f 2a01:111:f403:ca09::3 2a01:111:f403:ca09::4 52.101.68.10 52.101.68.25 52.101.73.153 52.101.73.8	mail-db7pr03cu00601.inbound.protection.outlook.com mail-db7pr03cu00507.inbound.protection.outlook.com mail-am6pr04cu00303.inbound.protection.outlook.com mail-am0pr04cu00504.inbound.protection.outlook.com mail-dbbpr03cu00102.inbound.protection.outlook.com mail-db8pr02cu00101.inbound.protection.outlook.com mail-as8pr05cu00401.inbound.protection.outlook.com mail-am0pr04cu00500.inbound.protection.outlook.com	AS8075 Microsoft Corporation AS8075 Microsoft Corporation AS8075 Microsoft Corporation AS8075 Microsoft Corporation AS8075 Microsoft Corporation AS8075 Microsoft Corporation AS8075 Microsoft Corporation AS8075 Microsoft Corporation

📧 Autodiscover / Autoconfig#

Service	CNAME / IP
🔷 Autodiscover	autodiscover.outlook.com → 40.104.116.8

🔷 AAAA Records (IPv6)#

2 records 285ms

IPv6 Address	TTL	PTR	ASN	ISP / Org	CIDR	Country	City
2606:4700:3037::6815:555e	300s	—	AS13335	Cloudflare, Inc.	2606:4700:3000:0:0:0:0:0/42	—	—
2606:4700:3037::ac43:cc40	300s	—	AS13335	Cloudflare, Inc.	2606:4700:3000:0:0:0:0:0/42	—	—

🔐 HTTPS Records#

1 records 410ms

Priority	Target	SvcParams
1 service	.	alpn="h3,h2" ipv4hint=104.21.85.94,172.67.204.64 ech=AEX+DQBBFAAgACASvhuD83qrl7ltzkLhfn02ly9tFbUssJeoutrqURGMeQAEAAEAAQASY2xvdWRmbGFyZS1lY2guY29tAAA= ipv6hint=2606:4700:3037::6815:555e,2606:4700:3037::ac43:cc40

🔌 SRV Records#

1 records 662ms

Service	Priority	Weight	Port	Target
_sipfederationtls._tcp	100	1	5061	sipfed.online.lync.com

📝 TXT Records#

1 records 958ms

TXT Record
v=spf1 a mx a:web01.c-system.dk a:windu.c-system.dk a:yoda.c-system.dk a:bb-8.c-system.dk ip4:49.12.60.82 ip4:87.61.82.67 include:spf.protection.outlook.com include:spf-eu.emailsignatures365.com -all

✉️ SPF#

Policy	Record (c-system.dk)
-all (hard fail)	v=spf1 a mx a:web01.c-system.dk a:windu.c-system.dk a:yoda.c-system.dk a:bb-8.c-system.dk ip4:49.12.60.82 ip4:87.61.82.67 include:spf.protection.outlook.com include:spf-eu.emailsignatures365.com -all

📨 DMARC#

Policy	Record (_dmarc.c-system.dk)
p=none (monitor only)	v=DMARC1; p=none; rua=mailto:5207a20c6d6740d1b84f2c2f82e879a4@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#

10 records 404ms

Flags	Tag	Value
0	issue	comodoca.com
0	issue	digicert.com; cansignhttpexchanges=yes
0	issue	letsencrypt.org
0	issue	pki.goog; cansignhttpexchanges=yes
0	issue	ssl.com
0	issuewild	comodoca.com
0	issuewild	digicert.com; cansignhttpexchanges=yes
0	issuewild	letsencrypt.org
0	issuewild	pki.goog; cansignhttpexchanges=yes
0	issuewild	ssl.com

🧩 Web & zone#

latest probe, not this scan · checked 2026-10-12 23:20:20

www	104.21.85.94 172.67.204.64 2606:4700:3037::6815:555e 2606:4700:3037::ac43:cc40 (AS13335) (address records, no CNAME)
www vs bare domain	Same network c-system.dk: 104.21.85.94 172.67.204.64 2606:4700:3037::6815:555e 2606:4700:3037::ac43:cc40 (AS13335) www.c-system.dk: 104.21.85.94 172.67.204.64 2606:4700:3037::6815:555e 2606:4700:3037::ac43:cc40 (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#

2 found

Selector	CNAME	Key
selector1	selector1-csystem-dk0c._domainkey.outrup.onmicrosoft.com	RSA · ~2048 bit
selector2	selector2-csystem-dk0c._domainkey.outrup.onmicrosoft.com	RSA · ~1024 bit below 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.

🔎 SPF check#

zone-wide SPF report

DNS lookups: 8/10 · policy: -all

warn 8 of the 10 allowed DNS lookups used: one more include can break SPF

🔏 ACME Challenge#

Type	Name	Value
TXT	_acme-challenge.c-system.dk	l1RXFV7Y-rAI6r49Z_uozZAb4dPIKbTKFrygPQoeLEg
TXT	_acme-challenge.c-system.dk	SCLmzI-uJrIxqnOc0QHZEIexGYiqmoXNekt0WNXhFLA

🔗 TLSA / DANE#

✗ No TLSA records — DANE not configured for HTTPS (_443) or MX (_25)

🔐 DNSSEC#

795ms

Check	Result
Validation Status	🔒 Secure
AD Flag (resolver validates)	✓ Set
DS Record	✓ Found
DNSKEY Record	✓ Found
Flags	fully validated

🏷️ SOA#

0ms

Field	Value
Serial	2412884301
Primary NS (MNAME)	autumn.ns.cloudflare.com
Responsible (RNAME)	dns@cloudflare.com
Refresh	10000s
Retry	2400s
Expire	604800s
Minimum (neg-cache TTL)	1800s

📋 Registration#

WHOIS fetched 2026-10-10 22:19:50

Field	Value
Registrar	CURANET A/S
Registered	2002-10-29
Expires	2027-07-31 (286d)

📋 WHOIS#

⏱️ Lookup Timing#

343ms

306ms

281ms

AAAA

285ms

TXT

958ms

CAA

404ms

HTTPS

410ms

TLSA

644ms

SOA

0ms

MTA-STS

450ms

DNSSEC

795ms

SRV

662ms

Total

10377ms

🕐 Scan History#

Scanned At	Duration	Records	DNSSEC
2026-10-12 23:20:20	1116ms	2 NS 2 A 1 MX	🔒 Secure
2026-10-11 23:16:48	5026ms	2 NS 2 A 1 MX	🔒 Secure
2026-10-10 22:03:03	5075ms	2 NS 2 A 1 MX	🔒 Secure
2026-09-30 11:21:52	1128ms	2 NS 2 A 1 MX	🔒 Secure
2026-09-29 07:30:21	1744ms	2 NS 2 A 1 MX	🔒 Secure
2026-09-27 06:52:21	1210ms	2 NS 2 A 1 MX	🔒 Secure
2026-09-10 22:47:48	2768ms	2 NS 2 A 1 MX	🔒 Secure
2026-08-31 13:24:18	1339ms	2 NS 2 A 1 MX	🔒 Secure
2026-08-24 01:09:09	10849ms	2 NS 2 A 1 MX	🔒 Secure
2026-08-23 00:20:58 shown	10377ms	2 NS 2 A 1 MX	🔒 Secure
2026-08-12 11:29:20	3885ms	2 NS 2 A 1 MX	🔒 Secure
2026-08-07 07:02:51	11375ms	2 NS 2 A 1 MX	🔒 Secure
2026-07-31 01:25:23	4018ms	2 NS 2 A 1 MX	🔒 Secure
2026-07-23 16:50:55	9431ms	2 NS 2 A 1 MX	🔒 Secure
2026-07-20 02:15:29	9551ms	2 NS 2 A 1 MX	🔒 Secure
2026-07-10 19:56:51	11264ms	2 NS 2 A 1 MX	🔒 Secure
2026-06-25 12:29:18	1775ms	2 NS 2 A 1 MX	🔒 Secure
2026-06-22 05:20:52	1146ms	2 NS 2 A 1 MX	🔒 Secure
2026-06-21 20:52:11	806ms	2 NS 2 A 1 MX	🔒 Secure
2026-06-16 18:45:31	953ms	2 NS 2 A 1 MX	🔒 Secure
2026-06-16 18:40:26	932ms	2 NS 2 A 1 MX	🔒 Secure