u21.dk

📜 Historical scan 2026-08-30 06:59:47 · ← Latest scan

⬇ Zone File 📜 Timeline & History ⚡ Scan Now

u21.dk is a .dk domain served by 3 nameservers (ns1.simply.com, ns2.simply.com, ns3.simply.com). It was registered on 21 January 2025 (WHOIS) and was already in the .dk zone when our tracking began on 16 June 2026. Mail is handled by mail.7a.dk. 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#

3 records 90ms

Nameserver	IP addresses	PTR	ASN / ISP
ns1.simply.com	2a02:2339:1:15c::4562:4562 91.197.248.78	ns1.simply.com ns1.simply.com	AS48854 team.blue Denmark A/S AS48854 team.blue Denmark A/S
ns2.simply.com	185.25.141.15 2a02:2339:4006:101::4562:4562	ns2.simply.com ns2.simply.com	AS48854 team.blue Denmark A/S AS48854 team.blue Denmark A/S
ns3.simply.com	91.197.248.79	ns3.simply.com	AS48854 team.blue Denmark A/S

🌍 A Records#

🌍

No A records found

📧 MX Records#

1 records 70ms

Priority	TTL	Mail Server	IP addresses	PTR	ASN
0	3600s	mail.7a.dk	2a00:fd01:8146:3d00:b314:f5ae:7d51:f73e	—	AS214875 Altibox Danmark AS

🔷 AAAA Records (IPv6)#

1 records 61ms

IPv6 Address	TTL	PTR	ASN	ISP / Org	CIDR	Country	City
2a00:fd01:8146:3d00:215:5dff:fe02:6d04	600s	—	AS214875	Altibox Danmark AS	2a00:fd01:0:0:0:0:0:0/32	🇩🇰 Denmark	Grindsted

🔐 HTTPS Records#

✗ No HTTPS RR — no SVCB/HTTPS service binding

📝 TXT Records#

1 records 263ms

TXT Record
v=spf1 include:spf.mailjet.com include:spf.simply.com -all

✉️ SPF#

Policy	Record (u21.dk)
-all (hard fail)	v=spf1 include:spf.mailjet.com include:spf.simply.com -all

📨 DMARC#

Policy	Record (_dmarc.u21.dk)
p=none (monitor only)	v=DMARC1; p=none;

📬 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 2026-10-11 09:07:10

www	188.228.54.119 (AS214875) (address records, no CNAME)
www vs bare domain	Same network u21.dk: 188.228.54.119 (AS214875) www.u21.dk: 188.228.54.119 (AS214875)
Wildcard	Yes: any name under the zone resolves
Denial of existence	NSEC zone can be walked (all names enumerable)
CDS / CDNSKEY	Published: key rollovers can be automated with the registry (RFC 7344/8078) 1 CDS, 1 CDNSKEY

🔎 SPF check#

zone-wide SPF report

DNS lookups: 2/10 · policy: -all

No problems found

🔗 TLSA / DANE#

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

🔐 DNSSEC#

195ms

Check	Result
Validation Status	🔒 Secure
AD Flag (resolver validates)	✓ Set
DS Record	✓ Found
DNSKEY Record	✓ Found
Flags	resolution failed: ncache nxrrset

🏷️ SOA#

0ms

Field	Value
Serial	2026082907
Primary NS (MNAME)	ns1.simply.com
Responsible (RNAME)	hostmaster@simply.com
Refresh	14400s
Retry	3600s
Expire	1209600s
Minimum (neg-cache TTL)	3600s

📋 Registration#

WHOIS fetched 2026-10-11 23:03:33

Field	Value
Registrar	Punktum dk A/S (direct)
Registered	2025-01-21
Expires	2027-01-20 (95d)

📋 WHOIS#

⏱️ Lookup Timing#

90ms

79ms

70ms

AAAA

61ms

TXT

263ms

CAA

119ms

HTTPS

100ms

TLSA

153ms

SOA

0ms

MTA-STS

112ms

DNSSEC

195ms

SRV

120ms

Total

1116ms

🕐 Scan History#

Scanned At	Duration	Records	DNSSEC
2026-10-03 02:35:07	780ms	3 NS 1 A 1 MX	🔒 Secure
2026-09-09 09:28:06	602ms	3 NS 1 A 1 MX	🔒 Secure
2026-08-31 12:06:09	661ms	3 NS 1 A 1 MX	🔒 Secure
2026-08-30 06:59:47 shown	1116ms	3 NS 0 A 1 MX	🔒 Secure
2026-08-29 00:01:53	643ms	3 NS 1 A 1 MX	🔒 Secure
2026-08-27 23:52:20	808ms	3 NS 1 A 1 MX	🔒 Secure
2026-08-27 02:11:21	566ms	3 NS 1 A 1 MX	🔒 Secure
2026-08-08 07:11:21	741ms	3 NS 1 A 1 MX	🔒 Secure
2026-07-03 09:00:41	2473ms	3 NS 1 A 1 MX	🔒 Secure
2026-06-27 21:11:59	1177ms	3 NS 1 A 1 MX	🔒 Secure
2026-06-26 01:23:11	434ms	3 NS 1 A 1 MX	🔒 Secure
2026-06-22 10:15:52	1166ms	0 NS 0 A 0 MX	❓ Unknown
2026-06-18 04:07:30	662ms	3 NS 1 A 1 MX	🔒 Secure